Solar cell module with rear contacts

ABSTRACT

A solar cell module with a simple configuration and high efficiency is provided. A solar cell module of the present invention is configured by electrically connecting a plurality of solar cell elements. Each of the plurality of solar cell elements includes a plurality of first connection parts representing wiring connection parts in a first electrode and a plurality of second connection parts representing wiring connection parts in a second electrode on the same surface. A first solar cell element and a second solar cell element arranged adjacent to each other have portions of the plurality of first connection parts of the first solar cell element and the plurality of second connection parts of the second solar cell element connected by a wiring having a linear form in plan view.

TECHNICAL FIELD

The present invention relates to a solar cell module.

BACKGROUND ART

A back contact type solar cell element is conventionally known as onetype of solar cell element (refer to, for example, Japanese Laid-OpenPatent Publication No. 63-211773 (Patent Document 1) and JapanesePublished Patent Publication No. 2002-500825 (Patent Document 2)).

The conventional solar cell element includes a semiconductor substrateexhibiting one conductivity type, a opposite conductivity type layerexhibiting a conductivity type opposite to the semiconductor substrate,a first electrode, and a second electrode having a polarity differentfrom the first electrode. The semiconductor substrate has a plurality ofthrough holes penetrating between a light receiving surface and a backsurface. The opposite conductivity type layer includes a first oppositeconductivity type layer arranged on the light receiving surface of thesemiconductor substrate, second opposite conductivity type layersarranged on the surfaces of the through holes of the semiconductorsubstrate, and a third opposite conductivity type layer arranged on theback surface side of the semiconductor substrate. The first electrodeincludes a light receiving surface electrode part formed on the lightreceiving surface side of the semiconductor substrate, through holeelectrode parts formed in the through holes, a bus bar electrode partformed at the ends of the back surface of the semiconductor substrateand a finger electrode part formed on the back surface of thesemiconductor substrate. The light receiving surface electrode part, thethrough hole electrode parts, the finger electrode part, and the bus barelectrode part are electrically connected. The second electrode isformed at a portion of the back surface of the semiconductor substratewhere the third opposite conductivity type layer is not formed.

The conventional solar cell module has a configuration in which the busbar electrodes of a plurality of solar cell elements, each having theabove configuration, are connected by wiring.

While wide spread use of the solar cell module using such a solar cellelement is further being expected, it is essential to enhance theconversion efficiency of solar light with a simple configuration. It isimportant to reduce the loss of photovoltaic power in enhancing theconversion efficiency.

DISCLOSURE OF THE INVENTION

In view of the above problems, it is an object of the present inventionto provide a highly efficient solar cell module with a simpleconfiguration.

A plurality of solar cell elements used in a solar cell module of thepresent invention include a power collecting part electrically connectedto a connection part, and surrounding the connection part. When theadjacent solar cell elements are first solar cell element and secondsolar cell element among the plurality of solar cell elements, thewiring connected to the connection part of the first solar cell elementand the connection part of the second solar cell element has a linearform in plan view.

According to such a configuration, the solar cell module of the presentinvention is made to a solar cell module in which loss of photovoltaicpower due to internal resistance is reduced and which has a simpleconfiguration and high conversion efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic view showing a structure of asolar cell element 10A according to a first embodiment of the presentinvention.

FIGS. 2A and 2B are plan views of the solar cell element 10A.

FIGS. 3A and 3B are diagrams schematically showing a configuration ofthe solar cell module 20A according to the first embodiment of thepresent invention.

FIGS. 4A and 4B are diagrams showing in detail the state of connectionof the solar cell elements 10A by wirings 11 in the solar cell module20A.

FIGS. 5A and 5B are plan views of a solar cell element 10B according toa second embodiment of the present invention.

FIGS. 6A to 6D are plan views of a solar cell element 10C and a solarcell element 10C′, which is a variation thereof, according to a thirdembodiment of the present invention.

FIGS. 7A and 7B are diagrams showing in detail the state of connectionof the solar cell elements 10C by the wirings 11 in a solar cell module20C according to the third embodiment of the present invention.

FIGS. 8A and 8B are schematic views of the entire solar cell module 20Caccording to the third embodiment and a solar cell module 20D accordingto a fourth embodiment according to the present invention when seen fromthe first surface 1F side in plan view.

FIGS. 9A and 9B are diagrams showing a solar cell element 10C″, which isa variation of the solar cell element 10C, and a solar cell module 20C″configured using the plurality of solar cell elements 10C″.

FIGS. 10A to 10D are plan views of a solar cell element 10D and a solarcell element 10D′ according to the fourth embodiment of the presentinvention.

FIGS. 11A and 11B are diagrams showing in detail the state of connectionof the solar cell elements 10D by the wirings 11 in the solar cellmodule 20D according to the fourth embodiment.

FIGS. 12A and 12 B are plan views of a solar cell element 10E accordingto a fifth embodiment of the present invention.

FIGS. 13A and 13B are diagrams showing in detail the state of connectionof the solar cell elements 10E by the wirings 11 in a solar cell module20E according to the fifth embodiment.

FIGS. 14A and 14B are plan views of a solar cell element 10F accordingto a sixth embodiment of the present invention.

FIGS. 15A and 15B are diagrams showing in detail the state of connectionof the solar cell elements 10F by the wirings 11 in a solar cell module20F according to the sixth embodiment.

FIGS. 16A to 16D are plan views of a solar cell element 10G and a solarcell element 10G′, which is a variation thereof, according to a seventhembodiment of the present invention.

FIGS. 17A and 17B are diagrams showing in detail the state of connectionof the solar cell element 10G and the solar cell element 10G′ by thewirings 11 in the solar cell module 20G according to the seventhembodiment.

FIGS. 18A and 18B are plan views of a solar cell element 10H accordingto an eighth embodiment of the present invention.

FIGS. 19A and 19B are diagrams showing in detail the state of connectionof the solar cell elements 10H by the wirings 11 in the solar cellmodule 20H according to the eighth embodiment.

FIGS. 20A and 20B are diagrams illustrating a different connection modebetween the solar cell elements 10H in the solar cell module 20Haccording to the eighth embodiment.

FIGS. 21A and 21B are plan views of a solar cell element 10I accordingto a ninth embodiment of the present invention.

FIGS. 22A and 22B are diagrams showing in detail the state of connectionof the solar cell elements 10I by the wirings 11 in the solar cellmodule 20I according to the ninth embodiment.

FIG. 23 is a plan view of a solar cell element 10J according to a tenthembodiment of the present invention.

FIGS. 24A to 24C are plan views of a solar cell element 10K according toan eleventh embodiment of the present invention.

FIGS. 25A to 25C are diagrams showing in detail the state of connectionof the solar cell elements 10K by the wirings 11 in the solar cellmodule 20K according to the eleventh embodiment.

FIGS. 26A to 26C are diagrams showing various variations according to astructure in a cross sectional direction of the solar cell element.

FIGS. 27A to 27D are diagrams showing another variations of the solarcell element.

FIGS. 28A to 28C are diagrams showing a solar cell module formed usingthe solar cell element according to the variation shown in FIG. 28.

FIGS. 29A and 29B are diagrams showing solar cell elements having fingerparts.

FIG. 30 is a diagram showing a solar cell element having a finger part.

FIG. 31 is a cross-sectional schematic view of a solar cell element 50formed with an insulating material layer 9 instead of being formed witha second opposite conductivity type layer 2 b and a third oppositeconductivity type layer 2 c.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of a solar cell module of the present inventionwill be described in detail with reference to the drawings.

First Embodiment

<Configuration of Solar Cell Element>

FIG. 1 is a cross-sectional schematic view showing a configuration of asolar cell element 10A according to a first embodiment of the presentinvention.

The solar cell element 10A includes a semiconductor substrate 1 of oneconductivity type, a opposite conductivity type layer 2 of aconductivity type different from the semiconductor substrate 1, a firstelectrode 4, and a second electrode 5.

The solar cell element 10A includes the semiconductor substrate 1 with afirst surface 1F (upper surface side in FIG. 1), and a second surface 1S(lower surface side in FIG. 1) on the back side of the first surface 1F.In the solar cell element 10A, the first surface 1F serves as a lightreceiving surface (for the sake of convenience of description, the firstsurface 1F is sometimes referred to as a light receiving surface or thelike of the semiconductor substrate 1).

A crystalline silicon substrate such as a single crystalline siliconsubstrate and a polycrystalline silicon substrate having a predetermineddopant element (impurities for conductivity type control) and exhibitingone conductivity type (e.g., p-type) is used as the semiconductorsubstrate 1. A mode of using a plate-shaped silicon obtained through apull-up method such as a ribbon method may be adopted. The thickness ofthe semiconductor substrate 1 is preferably less than or equal to 300μm, more preferably less than or equal to 250 μm, and even morepreferably less than or equal to 150 μm.

In the present embodiment, a case where a crystalline silicon substrateexhibiting a p-type conductivity type is used as the semiconductorsubstrate 1 will be described by way of example. When the semiconductorsubstrate 1 made of a crystalline silicon substrate exhibits p-type,boron or gallium is one suitable example for the dopant element. Inparticular, if gallium is used, the light deterioration phenomenon canbe reduced, and higher efficiency of the solar cell element can beachieved.

A texture structure (uneven structure) 1 a with a great number ofmicroscopic projections 1 b are formed on the side of the first surface1F of the semiconductor substrate 1 to reduce the reflection of theincident light at the first surface 1F and absorb more solar light intothe semiconductor substrate 1. The projections 1 b suitably have a widthand a height of less than or equal to 2 μm, and an aspect ratio(height/width) of greater than or equal to 0.1 and less than or equal to2. The texture structure 1 a is formed through methods such as wetetching and dry etching. The texture structure 1 a is not an essentialconfiguration in the present embodiment, and may be formed as necessary.

A plurality of through holes 3 is formed between the first surface 1Fand the second surface 1S in the semiconductor substrate 1. In FIG. 1,the cross section including only one through hole 3 is illustrated forthe sake of convenience of illustration. As hereinafter described, thethrough hole 3 has a second opposite conductivity type layer 2 b formedon the surface. A conductive part 4 b of the first electrode 4 is formedinside the through hole 3. The through holes 3 are preferably formed ata constant pitch with a diameter in the range of greater than or equalto 50 μm and less than or equal to 300 μm. The diameters of the throughhole 3 may differ between the first surface 1F and the second surface1S. The through holes 3 are formed with a mechanical drill, a water jet,a laser processing device, or the like.

The opposite conductivity type layer 2 is a layer that exhibits aconductivity type opposite to the semiconductor substrate 1. Theopposite conductivity type layer 2 includes a first oppositeconductivity type layer 2 a formed on the first surface 1F side of thesemiconductor substrate 1, a second opposite conductivity type layer 2 bformed on the surface of the through hole 3, and a third oppositeconductivity type layer 2 c formed on the second surface 1S side of thesemiconductor substrate 1. If a silicon substrate exhibiting aconductivity type of p-type is used for the semiconductor substrate 1,the opposite conductivity type layer 2 is formed to exhibit theconductivity type of n-type. This is realized by diffusing phosphorous(P) through thermal diffusion method or the like. The method of formingthe opposite conductivity type layer 2 will be described later indetail.

The first opposite conductivity type layer 2 a is suitably formed asn⁺-type having sheet resistance of about 60 to 300Ω/□. With such arange, increase in surface recombination and increase in surfaceresistance at the first surface 1F can be suppressed. In particular, ina case where the first opposite conductivity type layer 2 a is arrangedin combination with the texture structure 1 a, short-circuit current ofthe solar cell element 10A is greatly increased. The value of the sheetresistance can be measured through a four-probe method. For instance,four metal needles lined on a straight line are contacted to the surfaceof the semiconductor substrate 1 while applying pressure, current isflowed to two needles on the outer side, and the voltage generatedbetween two needles on the inner side is measured, whereby theresistance value is obtained from that voltage and the flowed current bythe Ohm's law.

The first opposite conductivity type layer 2 a is preferably formed to adepth of about 0.2 μm to 0.5 μm at the region other than the portionformed with the through hole 3 in the first surface 1F of thesemiconductor substrate 1. The third opposite conductivity type layer 2c merely needs to be formed at the peripheral part of the through hole 3in the second surface 1S of the semiconductor substrate 1.

A pn junction is formed between the opposite conductivity type layer 2and the bulk region of the semiconductor substrate 1 (region other thanthe opposite conductivity type layer 2) in the solar cell element 10A byincluding the opposite conductivity type layer 2.

The solar cell element 10A includes a high concentration doped layer 6inside the semiconductor substrate 1. The high concentration doped layer6 is a layer arranged with the aim of generating an internal electricfield inside the solar cell element 10A (with the aim of achieving aso-called BSF effect) to prevent lowering of power generation efficiencycaused by occurrence of carrier recombination in the vicinity of thesecond surface 1S of the semiconductor substrate 1. The highconcentration doped layer 6 is formed over substantially the entiresurface other than the vicinity of the through hole 3 on the side of thesecond surface 1S of the semiconductor substrate 1. More specifically,the high concentration doped layer 6 is formed so as not to contact thethird opposite conductivity type layer 2 c (so that the bulk region ofthe semiconductor substrate 1 exists in between) on the side of thesecond surface 1S. The specific formation pattern differs according tothe formation pattern of the first electrode 4.

“High concentration” herein means that a dopant element exists at aconcentration higher than the concentration of the dopant element thatis doped to exhibit one conductivity type in the semiconductor substrate1. The high concentration doped layer 6 is suitably formed, e.g., bydiffusing a dopant element such as boron or aluminum from the secondsurface 1S so that the concentration of the dopant element becomes about1×10¹⁸ to 5×10²¹ atoms/cm³. The high concentration doped layer 6 therebyexhibits a conductivity type of p⁺-type and realizes ohmic contact witha power collecting part 5 b to be described later.

If boron is the dopant element, the high concentration doped layer 6 canbe formed using thermal diffusion method with BBr₃ (boron tribromide) asa diffusion source. If aluminum is the dopant element, the highconcentration doped layer 6 can be formed by applying and firingaluminum paste containing aluminum powder, organic vehicle, and thelike.

The high concentration doped layer 6 is preferably formed to greaterthan or equal to 70% and less than or equal to 90% of the entire regionof the second surface 1S when the second surface 1S of the semiconductorsubstrate 1 is seen in plan view. In the case of greater than or equalto 70%, the BSF effect for enhancing the output characteristics of thesolar cell element 10A is obtained. The concentration is made to lowerthan or equal to 90% since it is necessary to ensure the region forforming a first connection part 4 c of the first electrode 4 and anon-formation region RE (described later) of the power collecting part 5b that becomes necessary with the formation of the first connection part4 c. In the solar cell element 10A of the present invention, however,the formation region of the first connection part 4 c can be madesmaller than in the conventional solar cell element as will be describedlater, and thus the high concentration doped layer 6 can be formed in asufficiently large range of at a maximum of 90% of the entire regionwhen the second surface 1S is seen in plan view.

The solar cell element 10A includes an antireflection coating 7 on thefirst surface 1F side of the semiconductor substrate 1. Theantireflection coating 7 serves to reduce the reflection of the incidentlight at the surface of the semiconductor substrate 1 and is formed onthe first opposite conductivity type layer 2 a. The antireflectioncoating 7 is suitably formed with a silicon nitride film (SiN_(x) film(composition ratio (x) ranges with Si₃N₄ stoichiometry as the center)),oxide material film (TiO₂ film, SiO₂ film, MgO film, ITO film, SnO₂film, ZnO film), or the like. The suitable value for the thickness ofthe antireflection coating 7 differs depending on the constitutingmaterial, but is set to a value that realizes nonreflecting conditionwith respect to the incident light. For instance, if a silicon substrateis used for the semiconductor substrate 1, the antireflection coating 7is formed with a material having an index of refraction of about 1.8 to2.3 to a thickness of about 500 to 1200 Å. The arrangement of theantireflection coating 7 is not essential in the present embodiment andmay be formed as necessary. The antireflection coating 7 is formedthrough PECVD method, vacuum deposition method, sputtering method, andthe like.

The first electrode 4 is configured by a main electrode part 4 a formedon the first surface 1F of the semiconductor substrate 1, a firstconnection part 4 c formed on the second surface 1S, and a conductionpart 4 b arranged in the through hole 3 for electrically connecting themain electrode part 4 a with the first connection part 4 c. The mainelectrode part 4 a has a function of collecting carriers generated atthe first surface 1F, and the first connection part 4 c serves as awiring connection part for connecting external wirings. The mainelectrode part 4 a, the conduction part 4 b, and the first connectionpart 4 c are formed by applying conductive paste containing metallicpowder on the first surface 1F (for the main electrode part 4 a and theconduction part 4 b) or the second surface 1S (for the first connectionpart 4 c) of the semiconductor substrate 1 in a predetermined electrodepattern, and then firing the same.

On the other hand, the second electrode 5 has a polarity different fromthe first electrode 4 and is configured by a second connection part (busbar part) 5 a and a power collecting part 5 b surrounding the secondconnection part 5 a. The power collecting part 5 b is formed on the highconcentration doped layer 6 formed on the side of the second surface 1Sof the semiconductor substrate 1 and collects carriers generated on theside of the second surface 1S. The second connection part 5 a serves asa wiring connection part for connecting external wirings. When formingboth the parts, at least part of the second connection part 5 a ispreferably configured to overlap with the power collecting part 5 b.

The power collecting part 5 b is formed, e.g., by applying conductivepaste containing aluminum and silver as the metallic powder on the highconcentration doped layer 6 in a predetermined electrode pattern, andthen firing the same. If aluminum paste is used for the conductivepaste, the high concentration doped layer 6 and the power collectingpart 5 b can be simultaneously formed, as will be described later.

The second connection part 5 a is formed by applying conductive pastecontaining silver as a main component as the metallic powder on the highconcentration doped layer 6 in a predetermined electrode pattern, andthen firing the same. The second connection part 5 a is therebyelectrically connected to the power collecting part 5 b.

If silver is used for the second connection part 5 a, and aluminum isused for the power collecting part 5 b, the second connection part 5 apreferably contains zinc or a zinc alloy. According to such aconfiguration, the rise in resistance between the power collecting part5 b and the second connection part 5 a can be reduced. In particular, inthe case of being formed to contain zinc or a zinc alloy at greater thanor equal to 7 parts by weight and lower than or equal to 35 parts byweight with respect to silver of 100 parts by weight, the outputcharacteristics of the solar cell element 10A further less likely tolower.

According to such a configuration, there is realized a solar cellelement 10A having n⁺/p/p⁺ junction of the opposite conductivity typelayer 2, the semiconductor substrate 1, and the high concentration dopedlayer 6 between the first electrode 4 and the second electrode 5.

FIGS. 2A and 2B are plan views of the solar cell element 10A showing oneexample of the electrode patterns of the first electrode 4 and thesecond electrode 5. FIG. 2A is a diagram of the solar cell element 10Aseen from the side of the second surface 1S in plan view (also referredto as a back surface view), and FIG. 2B is a diagram of the solar cellelement 10A seen from the side of the first surface 1F in plan view(also referred to as a light receiving surface view). To facilitate theunderstanding on the relationship between the electrode pattern arrangedon the side of the first surface 1F and the electrode pattern arrangedon the side of the second surface 1S, the electrode patterns in arelationship where the front and back surfaces of the solar cell element10A are actually inverted is not shown in FIGS. 2A and 2B, andillustration is made such that the electrode pattern on the back surfaceside in the case where the solar cell element 10A is virtually seenthrough from the light receiving surface side shown in FIG. 2B has arelationship corresponding to the electrode pattern shown in FIG. 2A.Although not mentioned, this holds true for the subsequent figures in asimilar relationship.

As shown in FIG. 2B, a plurality of conduction parts 4 b is formed inthe solar cell element 10A in correspondence to the plurality of throughholes 3 formed in the semiconductor substrate 1. That is, the formationpositions of the conduction parts 4 b shown in black dots in FIG. 2Bcorrespond to the formation positions of the through holes 3. In thepresent embodiment, there is shown a case where the plurality of throughholes 3 is formed so that an array of a plurality of columns (threecolumns in FIG. 2B) is formed parallel to a direction (directioninclined by an inclination angle θ with respect to a base side BS of thefirst surface 1F of the semiconductor substrate 1) shown with an arrowAR1 in FIG. 2B, and the conduction part 4 b is formed inside each of theplurality of through holes 3. The base side BS is the side parallel tothe arraying direction in the case of arraying the plurality of solarcell elements 10A whereby to form the solar cell module 20A. Thedirection along the base side BS (direction parallel to the base sideBS) is referred to as a reference direction. In FIG. 2B, the throughholes 3 are arranged so as to be arrayed in a plurality of (three inFIGS. 2A and 2B) straight lines, and the solar cell element 10A includesthe through holes 3 (conduction parts 4 b) formed at substantially equalintervals.

It is to be noted that the term “parallel” in the present descriptionshould not be strictly defined as in a mathematical definition.

Furthermore, the main electrode parts 4 a are formed on the firstsurface 1F as a plurality of linear patterns connecting with theplurality of (three in FIG. 2B) conduction parts 4 b belonging todifferent arrays. Such main electrode parts 4 a are suitably formed tohave a line width of about 50 to 100 μm. Thus, when light is evenlyemitted onto the first surface 1F, concentrating of the current flow atone conduction part 4 b, and increase in the resistance loss is reduced.The output characteristics of the solar cell element are thus lesslikely to lower. The pattern of the main electrode parts 4 a is notlimited to that shown in FIG. 2B, and various patterns can be formed(this holds true for the subsequent embodiments).

In addition, in the solar cell element 10A, high light receivingefficiency is realized since the occupying proportion of the mainelectrode parts 4 a configuring the first electrode 4 is very smallcompared to the entire surface of the first surface 1F, or the lightreceiving surface, and the carriers generated at the first surface 1Fcan be efficiently collected since the main electrode parts 4 a areuniformly formed.

Meanwhile, as shown in FIG. 2A, the first connection parts 4 c having anelongated shape (parallelogram) with a longitudinal direction in thearraying direction of the conduction parts 4 b (i.e. having a bandform), and being connected to the conduction parts 4 b are formed atpositions immediately below the plurality of conduction parts 4 b(through holes 3) at the second surface 1S of the semiconductorsubstrate 1. The first connection parts 4 c are formed in plural (threein FIG. 2A) in correspondence to the array of the conduction parts 4 b.

The power collecting part 5 b is formed over substantially the entiresurface of the second surface 1S excluding the first connection parts 4c, the peripheral portion of the first connection parts 4 c, and thesecond connection parts 5 a of the second electrodes 5. “Substantiallythe entire surface” herein refers to the case where the power collectingpart 5 b is formed at greater than or equal to 70% and less than orequal to 90% of the entire region of the second surface 1S when thesecond surface 1S of the semiconductor substrate 1 is seen in plan view.The region near the edge surfaces of the semiconductor substrate 1 ofthe solar cell element 10A that is not formed with the first connectionparts 4 c but is to be covered by a wiring 11 during the formation ofthe solar cell module 20A, as will be described later, is assumed as anon-formation region RE where the power collecting part 5 b is notformed to prevent the wiring 11 from contacting the power collectingpart 5 b whereby to reduce the occurrence of leakage. The arrangement ofthe power collecting part 5 b over substantially the entire surfaceother than the region formed with the first connection parts 4 c and thenon-formation region RE shortens the movement distances of the carrierscollected at the power collecting part 5 b and increases the amount ofcarriers to be retrieved from the second connection parts 5 a, and thuscontributes to enhancement of the output characteristics of the solarcell element 10A.

Furthermore, the second connection parts 5 a are arranged so that atleast parts thereof overlap with the power collecting part 5 b. Theplurality of second connection parts 5 a (three in correspondence to thefirst connection parts 4 c in FIG. 2A), has an elongated shape(parallelogram) similar to the first connection parts 4 c (i.e., havinga band form) in a mode of being parallel to each of the plurality offirst connection parts 4 c. The formation position of each secondconnection part 5 a (in particular, formation interval with the adjacentfirst connection part 4 c) is defined according to the arrangementinterval of the adjacent solar cell elements 10A in the case where theplurality of solar cell elements 10A is arranged adjacent to each other(in the case of configuring a solar cell module). This will be describedlater.

<Solar Cell Module>

The solar cell element 10A according to the present embodiment can beused alone, but a suitable structure is obtained by adjacently arranginga plurality of solar cell elements 10A having the same structure andconnecting the same in series to one another to configure a module. Thesolar cell module formed using the plurality of solar cell elements 10Awill be described below.

FIGS. 3A and 3B are diagrams schematically showing a configuration ofsuch a solar cell module 20A. FIG. 3A is a cross-sectional view of thesolar cell module 20A, and FIG. 3B is a front view of the solar cellmodule 20A seen from the light receiving surface side.

As shown in FIG. 3A, the solar cell module 20A mainly includes atranslucent member 12 made of glass and the like, a surface side filler24 made of transparent ethylene-vinyl acetate copolymer (EVA) and thelike, the plurality of solar cell elements 10A, a back side filler 15made of EVA and the like, and a back surface protective member 13 havingpolyethylene telephthalate (PET) or a metal foil sandwiched withpolyvinyl fluoride resin (PVF) and the like. The plurality of solar cellelements 10A has the adjacent solar cell elements 10A connected inseries to each other with the wirings 11 serving as a connection member.

FIGS. 4A and 4B are diagrams showing the detail of connection of thesolar cell elements 10A by the wirings 11 in the solar cell module 20A.FIG. 4A is a diagram of two solar cell elements 10A adjacent to eachother in the solar cell module 20A seen in plan view from the side ofthe second surface 1S. FIG. 4B is a diagram of the same in plan viewseen from the side of the first surface 1F.

FIGS. 3A and 3B only show schematic cross sections, but one firstconnection part 4 c of one of the adjacent solar cell elements 10A andone second connection part 5 a of the other solar cell element 10A areconnected by an elongated (linear) wiring 11 in the solar cell module20A, as shown in FIG. 4A. In the case of FIGS. 4A and 4B, connection ismade at three locations. In the following description, of the two solarcell elements 10A connected by the wirings 11 in FIGS. 4A and 4B, thesolar cell element 10A having the wiring 11 connected to the firstconnection part 4 c is referred to as a first solar cell element 10Aα,and the solar cell element 10A having the wiring connected to the secondconnection part 5 a is referred to as a second solar cell element 10Aβ,for the sake of convenience.

More specifically, in the solar cell module 20A, the first solar cellelement 10Aα and the second solar cell element 10Aβ are arranged suchthat the respective base sides BS are positioned on the same straightline and so that the longitudinal directions of the first connectionparts 4 c of the first solar cell element 10Aα and the longitudinaldirections of the corresponding second connection parts 5 a of thesecond solar cell element 10Aβ are positioned on substantially the samestraight line. The first solar cell element 10Aα and the second solarcell element 10Aβ are connected by the linear wirings 11 in plan view onsubstantially the same straight line. This is because the arrangementmode of the first connection parts 4 c and the second connection parts 5a (e.g., inclination angle θ, spacing between the first connection part4 c and the second connection part 5 a, and the like) is defined so thatthe first connection parts 4 c of the first solar cell element 10Aα andthe second connection parts 5 a of the second solar cell element 10Aβsatisfy the above positional relationship in the case where the solarcell elements 10A are adjacently arranged at a predetermined distance w.In other words, the first connection parts 4 c and the second connectionparts 5 a are arranged so that the first solar cell element 10Aα and thesecond solar cell element 10Aβ are electrically connectable with theplurality of wirings 11 in the case where the first solar cell element10Aα and the second solar cell element 10Aβ are arranged at a distance wso as to be translationally symmetric to each other.

The inclination angle θ is preferably greater than or equal to 0.3degrees and less than or equal to 15 degrees if a semiconductorsubstrate 1 of 15 cm squares is used. If the size of one side of thesemiconductor substrate 1 is greater than or equal to 15 cm, a smallervalue may be adopted. In this case, since it can be seen as if thewirings 11 are formed substantially perpendicular to one side of therectangular semiconductor substrate 1, a beautiful appearance isobtained.

In the solar cell module 20A, the relative arrangement relationshipamong the sets of the first connection part 4 c and the secondconnection part 5 a in a relationship of being connected with one wiring11 is equivalent (i.e., sets of first connection part 4 c and secondconnection part 5 a are all in translationally symmetric relationship)excluding the solar cell element 10A arranged at the ends, and thus thewiring 11 having the same shape can be used for the connection of theeach set of the first connection part 4 c and the second connection part5 a.

A wiring, e.g., having a thickness of about 0.1 to 0.4 mm and a width ofabout 2 mm, and having a band shaped copper foil with the entire surfacecovered by a solder material cut into a predetermined length in thelongitudinal direction can be used for the wiring 11. In the case of thewiring 11 covered with a solder material, it is soldered to the firstconnection part 4 c and the second connection part 5 a of the solar cellelement 10A using hot air or a soldering iron, or using a reflow furnaceand the like.

In the solar cell module 20A connected with the wirings 11 in such amode, the plurality of first connection parts 4 c is individually anddirectly connected to the second connection parts 5 a of the adjacentsolar cell elements, as opposed to the conventional solar cell module inwhich connection by one wiring is carried out at the bus bar partarranged at the end of the solar cell element, and thus a path of acollecting current from each main electrode part 4 a is shortened. Thus,the loss of photovoltaic power due to the internal resistance is lesslikely to occur than in the conventional solar cell module.

The wiring 11 merely needs to be connected to one portion of each of thefirst connection part 4 c and the second connection part 5 a as long asthe connection therebetween is sufficiently obtained (resistance issufficiently small), and need not necessarily be arranged so as to coverthe entire first connection part 4 c and the second connection part 5 a.Regarding the connection of the first connection part 4 c and the wiring11, the wiring 11 is arranged so that the wiring 11 exists at theportion immediately below the through hole 3 (conduction part 4 b).Since the wiring 11 also exists as the conductive member in addition tothe first connection part 4 c immediately below the through hole 3 wherethe wiring 11 is arranged, and thus the cross sectional area of theconductive portion becomes larger. Thus, the reduction in the conductionresistance in retrieving the collecting current is realized.

An effect of facilitating the positioning of the wirings 11 inconnection is obtained by arranging the first connection parts 4 c ofthe first solar cell element 10Aα and the second connection parts 5 a ofthe second solar cell element 10Aβ on the same straight lines. That is,there is obtained an effect that the connection step of the solar cellelement 10A and the wirings 11 is less likely to become complicated.

Furthermore, in the solar cell module 20A according to the presentembodiment, the wirings 11 are arranged connecting only with the firstconnection parts 4 c and the second connection parts 5 a arranged on theside of the second surface 1S of the solar cell element 10A, and thusthe wirings 11 need not be bent to be connected on the first surface 1Fside as in the conventional solar cell module. Accordingly, the wiringsare less likely to be stripped from the electrodes.

In addition, the solar cell elements 10A are connected only at thesecond surface 1S side, and thus the region the wirings 11 that haveglaze due to the metal raw material is relatively small when the solarcell module is seen from the first surface 1F side or the lightreceiving surface side, as shown in FIG. 4B. Thus, the aestheticappearance of the solar cell module 20A is not affected.

If a material having high reflectance such as a white material is usedfor the back surface protective member 13, the solar cell elements 10Aare irradiated with light such that the light emitted between the solarcell elements 10A is reflected diffusely, and thus the light receivingquantity at the solar cell elements 10A further increases.

<Manufacturing Method of the Solar Cell Element>

A method of manufacturing the solar cell element will be described next.

(Step of Preparing a Semiconductor Substrate)

First, a semiconductor substrate 1 exhibiting a conductivity type ofp-type is prepared.

If a single crystalline silicon substrate is used for the semiconductorsubstrate 1, the semiconductor substrate 1 can be obtained by cuttingout a single crystalline silicon ingot made through a knownmanufacturing method such as FZ and CZ method to a predeterminedthickness. If a polycrystalline silicon substrate is used for thesemiconductor substrate 1, the semiconductor substrate 1 is obtained bycutting out a polycrystalline silicon ingot made through a knownmanufacturing method such as casting method and in-mold solidifyingmethod to a predetermined thickness. If a plate-shaped silicon obtainedthrough a pull-up method such as ribbon method is used, the plate-shapedsilicon is cut into a predetermined size, and a surface polishingprocess and the like are performed as necessary to obtain a desiredsemiconductor substrate 1.

In the following, a case of using a crystalline silicon substrateexhibiting a conductivity-type of p-type obtained by doping B or Ga asthe dopant element to about 1×10¹⁵ to 1×10¹⁷ atoms/cm³ is used for thesemiconductor substrate 1 will be described by way of example. Thedoping of the dopant element can be realized by dissolving anappropriate amount of the dopant element itself or a dopant materialcontaining an appropriate amount of the dopant element in silicon into asilicon solution in each silicon ingot manufacturing method describedabove.

In order to remove a mechanically damaged layer or polluted layer of thesurface layer of the semiconductor substrate 1 involved in cut-out(slicing), each surface layer on the front surface side and the backsurface side of the cut-out semiconductor substrate 1 is etched by about10 to 20 μm with NaOH and KOH, a mixed liquid of hydrofluoric acid andnitric acid, or the like and then washed with pure water to removeorganic components and metal components.

<Through Hole Formation Step>

A through hole 3 is formed between the first surface 1F and the secondsurface 1S of the semiconductor substrate 1.

The through hole 3 is formed using a mechanical drill, a water jet, alaser processing device, or the like. In such a case, the processing isperformed from the second surface 1S side towards the first surface 1Fside of the semiconductor substrate 1 to avoid the first surface 1F tobe the light receiving surface from being damaged. However, if thedamage on the semiconductor substrate 1 by the processing is small, theprocessing may be performed from the first surface 1F side towards thesecond surface 1S side.

<Texture Structure Formation Step>

A texture structure 1 a having microscopic projections (convex parts) 1b to effectively reduce the light reflectance is formed on the lightreceiving surface side of the semiconductor substrate 1 formed with thethrough hole 3.

The method of forming the texture structure 1 a includes a wet etchingmethod with an alkaline aqueous solution such as NaOH and KOH, and a dryetching method using an etching gas having a property of etching Si.

When the wet etching method is used, the second surface 1S side ispreferably masked with an etching preventive material to preventconcave/convex parts from forming on the second surface 1S side of thesemiconductor substrate 1.

When the dry etching method is used, the microscopic texture structure 1a can be formed basically only on the processing surface side (firstsurface 1F side). When RIE method (Reactive Ion Etching method) is usedfor the dry etching method, the microscopic texture structure 1 acapable of suppressing the light reflectance to a very low degree over awide wavelength range can be formed over a wide area in a short periodof time, which is very effective in enhancing the efficiency of thesolar cell element 10A. In particular, since the RIE method is capableof forming the concave-convex structure without being greatly influencedby plane orientation of the crystal, the microscopic texture structure 1a having low reflectance can be uniformly formed over the entiresubstrate irrespective of the plane orientation of each crystal grain inthe polycrystalline silicon substrate even if a polycrystalline siliconsubstrate is used for the semiconductor substrate 1.

<Opposite Conductivity Type Layer Formation Step>

A opposite conductivity type layer 2 is then formed. That is, the firstopposite conductivity type layer 2 a is formed on the first surface 1Fof the semiconductor substrate 1, the second opposite conductivity typelayer 2 b is formed on the surface of the through hole 3, and the thirdopposite conductivity type layer 2 c is formed on the second surface 1S.

In the case of using a crystalline silicon substrate exhibiting aconductivity type of p-type as the semiconductor substrate 1, P(phosphorous) is preferably used for the n-type doping element forforming the opposite conductivity type layer 2.

The opposite conductivity type layer 2 is formed by an application andthermal diffusion method of applying P₂O₅ in a paste form to formationtarget locations on the semiconductor substrate 1 and thermallydiffusing the same, a gaseous phase thermal diffusion method ofdiffusing to the formation target locations with POCI₃ (phosphorousoxychloride) in a gas form as the diffusion source, an ion implantationmethod of diffusing P⁺ ions directly to the location to be formed withthe opposite conductivity type layer 2, and the like. The gaseous phasethermal diffusion method is preferably used since the oppositeconductivity type layers 2 can be simultaneously formed at the formationtarget locations on both main surfaces of the semiconductor substrate 1and the surface of the through hole 3.

Under the conditions where a diffusion region is formed other than theformation target locations, the opposite conductivity type layer 2 maybe formed after forming a diffusion preventive layer in advance at thatportion, thereby partially preventing the diffusion. Alternatively, thediffusion region formed other than the formation target locations may besubsequently etched and removed without forming the diffusion preventivelayer. If the high concentration doped layer 6 is formed with aluminumpaste, as will be described later, after the formation of the oppositeconductivity type layer 2, aluminum or a p-type dopant element can bediffused to a sufficient depth at a sufficient concentration, and thusthe presence of the shallow diffusion region that has been alreadyformed can be ignored. That is, the opposite conductivity type layer 2existing at the location to be formed with the high concentration dopedlayer 6 need not be particularly removed. In such a case, an etchingpaste of glass and the like is applied and fired only at the peripheriesof the regions to be formed with the first connection parts 4 c toperform pn isolation.

<Antireflection Coating Formation Step>

Next, the antireflection coating 7 is preferably formed on the firstopposite conductivity type layer 2 a.

A PECVD method, a deposition method, a sputtering method, and the likemay be employed for the method of forming the antireflection coating 7.If the antireflection coating 7 made of SiNx film is formed through thePECVD method, the antireflection coating 7 is formed by diluting a mixedgas of silane (Si₃H₄) and ammonia (NH₃) with nitrogen (N₂) with theinside of the reaction chamber at 500° C., and thereafter forming thediluted gas into plasma with glow discharge degradation and depositingthe same.

The antireflection coating 7 may be formed while patterning with apredetermined pattern so that the antireflection coating 7 is not formedat the locations to be formed with the main electrode parts 4 a later.The patterning method includes, in addition to the method of removingthe antireflection coating 7 at the locations to be formed with the mainelectrode parts 4 a using an etching method (wet etching or dry etching)using a mask such as resist, a method of forming a mask in advance priorto the formation of the antireflection coating 7, and removing the sameafter forming the antireflection coating 7.

Alternatively, instead of employing the patterning method, a so-calledfire-through method of uniformly forming the antireflection coating 7,and thereafter, directly applying conductive paste for forming the mainelectrode parts 4 a on the surface of the antireflection coating 7 andat the location to be formed with the main electrode parts 4 a, andfiring the same to electrically contact the main electrode parts 4 awith the first opposite conductivity type layer 2 a. The fire throughmethod will be described later.

<High Concentration Doped Layer Formation Step>

The high concentration doped layer 6 is formed on the second surface 1Sof the semiconductor substrate 1.

In the case of using boron for the dopant element, the highconcentration doped layer 6 can be formed at a temperature of about 800to 1100° C. through the thermal diffusion method having BBr₃(phosphorous tribromide) as the diffusion source. In this case, prior tothe formation of the high concentration doped layer 6, a diffuse barriermade of oxide film and the like is formed on a region other than thelocation to be formed with the high concentration doped layer 6 such asthe already formed opposite conductivity type layer 2, and is desirablyremoved after forming the high concentration doped layer 6.

In the case of using aluminum for the dopant element, the highconcentration doped layer 6 can be formed by applying aluminum pastemade of aluminum powder, organic vehicle, and the like on the secondsurface 1S of the semiconductor substrate 1 through a printing method,and thereafter performing thermal treatment (firing) at a temperature ofabout 700 to 850° C. to diffuse aluminum towards the semiconductorsubstrate 1. In this case, the high concentration doped layer 6 of thedesired diffusion region can be formed only on the second surface 1S ofthe printed surface of the aluminum paste. Furthermore, a layer ofaluminum formed on the second surface 1S can be used as a powercollecting part 5 b without being removed after the firing.

<Electrode Formation Method>

The main electrode parts 4 a and the conduction parts 4 b configuringthe first electrode 4 is then formed.

The main electrode parts 4 a and the conduction parts 4 b are formedusing an application method. Specifically, the main electrode parts 4 aand the conduction parts 4 b can be formed by applying a conductivepaste, which is obtained by, e.g., adding organic vehicle of 10 to 30parts by weight and glass frit of 0.1 to 10 parts by weight with respectto 100 parts by weight of metal powder of silver and the like, to thefirst surface 1F of the semiconductor substrate 1 with formationpatterns of the main electrode parts 4 a shown in FIG. 2B thereby toform an applied film, and thereafter, firing the applied film for aboutseveral tens seconds to several tens minutes at a maximum temperature of500 to 850° C. In this case, the conduction parts 4 b are formed byfilling the conductive paste into the through holes 3 when applying theconductive paste. However, the conductive paste is applied from thesecond surface 1S side when forming the first connection parts 4 c, aswill be described later, in which case the conductive paste is againfilled into the through holes 3 and thereafter fired, and thus thethrough holes 3 need not be sufficiently filled with the conductivepaste when applying the conductive paste to the first surface 1F.

After applying the conductive paste and before the firing, the solventin the applied film is preferably evaporated at a predeterminedtemperature to dry the applied film. The main electrode parts 4 a andthe conduction parts 4 b may be formed by respective application/filing,e.g., filling and drying the conductive paste only in the through holes3 in advance, and thereafter, applying and firing the conductive pastein the patterns of the main electrode parts 4 a as shown in FIG. 2B, asdescribed above.

In the case where the antireflection coating 7 is formed prior to theformation of the main electrode parts 4 a as described above, the mainelectrode parts 4 a are formed in the patterned region or the mainelectrode parts 4 a are formed by the fire through method.

In the case of forming the main electrode parts 4 a by the fire throughmethod, a fire-through-use conductive paste in which, e.g., the glassfrit contains a lead glass frit or phosphorous in the conductive pasteis applied on the antireflection coating, and fired at a hightemperature of higher than or equal to 800° C. to fire through theantireflection coating 7.

Alternatively, the antireflection coating 7 may be formed after formingthe main electrode parts 4 a. In this case, the antireflection coating 7need not be patterned and the fire-through method need not be employed,and thus the conditions for forming the main electrode parts 4 a arealleviated. For example, the main electrode parts 4 a can be formedwithout performing firing at a high temperature of about 800° C.

The power collecting part 5 b is then formed on the second surface 1S ofthe semiconductor substrate 1.

An application method can be used to form the power collecting part 5 b.Specifically, the power collecting part 5 b is formed by applying aconductive paste, which is obtained by adding organic vehicle of 10 to30 parts by weight and a glass frit of 0.1 to 5 parts by weight withrespect to 100 parts by weight of metal powder of aluminum, silver, orthe like, to the second surface 1S of the semiconductor substrate 1 witha formation pattern of the power collecting part 5 b shown in FIG. 2Athereby to form an applied film, and thereafter, firing the applied filmfor about several tens seconds to several tens minutes at a maximumtemperature of 500 to 850° C. As described above, the high concentrationdoped layer 6 and the power collecting part 5 b can be simultaneouslyformed if aluminum paste is used.

Furthermore, the first connection parts 4 c and the second connectionparts (bus bar parts) 5 a are formed on the second surface 1S of thesemiconductor substrate 1.

The first connection parts 4 c and the second connection parts 5 a canbe simultaneously formed using an application method. Specifically, thefirst connection parts 4 c and the second connection parts 5 a areformed by applying a conductive paste, which is obtained by adding anorganic vehicle of 10 to 30 parts by weight and a glass frit of 0.1 to 5parts by weight to a metal powder of 100 parts by weight such as silver,to the second surface 1S of the semiconductor substrate 1 with theformation patterns of the first connection parts 4 c and the secondconnection parts 5 a shown in FIG. 2A thereby to form an applied film,and thereafter, firing the applied film for about several tens secondsto several tens minutes at a maximum temperature of 500 to 850° C.

The first connection parts 4 c and the second connection parts 5 a maybe respectively formed or may be formed using conductive pastes ofdifferent compositions. For instance, the conductive paste for formingthe second connection parts 5 a may contain silver and zinc or a zincalloy as the metal powder. For instance, when the second connectionparts 5 a are formed using a conductive paste containing zinc or a zincalloy of greater than or equal to 7 parts by weight and less than orequal to 35 parts by weight with respect to silver of 100 parts byweight, organic vehicle of 10 to 30 parts by weight, and a glass frit of0.1 to 5 parts by weight, the rise in series resistance between thesecond connection parts 5 a and the power collecting part 5 b lowers.

The solar cell element 10A according to the present embodiment can bemanufactured through the above procedure.

A solder region (not shown) may be formed on the first connection parts4 c and the second connection parts 5 a through a solder dippingprocess, as necessary.

<Method of Manufacturing the Solar Cell Module>

A method of manufacturing the solar cell module 20A using the solar cellelement 10A formed as above will be described next.

First, the entire surface of a copper foil having a thickness of about0.1 to 0.4 mm and a width of about 2 mm is covered with a soldermaterial in advance, and then cut to a predetermined length in thelongitudinal direction to fabricate the wirings 11.

As shown in FIG. 4A, the plurality of solar cell elements 10A is mountedwith the second surfaces 1S facing upward, spaced at a predetermineddistance w, and the wirings 11 are contacted between the firstconnection parts 4 c of the first solar cell element 10Aα and the secondconnection parts 5 a of the second solar cell element 10Aβ from theupper side. In this state, the solder at the surface of the wirings 11is melted using hot air or a soldering iron, or a reflow furnace toconnect the wirings 11 to the first connection parts 4 c and the secondconnection parts 5 a. According to such a method, the solar cellelements 10A can be connected at high productivity.

Subsequently, a module base obtained by sequentially stacking a frontside filler 24, the plurality of solar cell elements 10A connected toone another by the wirings 11, a back side filler 15, and the backsurface protective member 13 on the translucent member 12 is deaired,heated, and pressed in a laminator to integrate the layers, therebyobtaining the solar cell module 20A.

As shown in FIG. 3B, a frame 18 made of aluminum and the like is fittedto the outer periphery of the above-described solar cell module 20A. Asshown in FIG. 3A, the ends of the electrodes of the first solar cellelement 10A and the last solar cell element 10A of the plurality ofsolar cell elements 10A connected in series are connected to a terminalbox 17, which is an output retrieving unit, by an output retrievingwiring 16.

The solar cell module 20A according to the present embodiment can beobtained according to such a procedure.

Second Embodiment

The arrangement mode of the solar cell module according to the presentinvention and the first electrode and the second electrode in the solarcell element configuring the same is not limited to that described inthe first embodiment. A different arrangement mode of the firstelectrode and the second electrode will be hereinafter describedsequentially in each embodiment. In all of the embodiments describedbelow, effects similar to the solar cell element and the solar cellmodule according to the first embodiment can be obtained. However, inall the embodiments, the elements configuring the solar cell module andthe solar cell element are the same as in the first embodiment, and thecross-sectional structure near the through holes is the same as in FIG.1, and thus the same reference numerals as in the first embodiment aregiven for components having the same function, and the detaileddescription thereof will not be repeated.

First, a solar cell element 10B according to the second embodiment willbe described with reference to FIGS. 5A and 5B.

FIGS. 5A and 5B are plan views of the solar cell element 10B showing oneexample of electrode patterns of the first electrode 4 and the secondelectrode 5 in the solar cell element 10B. FIG. 5A is a diagram showingthe solar cell element 10B when seen in plan view from the secondsurface 1S side, and FIG. 5B is a diagram showing the solar cell element10B when seen in plan view from the first surface 1F side.

As shown in FIG. 5A, a plurality of columns (three columns in FIG. 5A)in which a plurality of (five in FIG. 5A) first connection parts 4 chaving a parallelogram shape is lined in a direction indicated with anarrow AR2 (direction inclined by the same angle θ as the inclinationangle θ of the first connection parts 4 c and the second connectionparts 5 a in the solar cell element 10A according to the firstembodiment) is formed, and a plurality of columns (three columns in FIG.5A) including a plurality of (five in FIG. 5A) second connection parts 5a having a parallelogram shape lined in a direction of the arrow AR2 tolie along the columns of the first connection parts 4 c is formed on thesecond surface 1S side of the solar cell element 10B. In such a case,the relationship between the columns of the first connection parts 4 cand the columns of the second connection parts 5 a can be assumed assubstantially the same as the relationship between the first connectionparts 4 c and the second connection parts 5 a of the solar cell element10A according to the first embodiment. In other words, the solar cellelement 10B has a configuration in which the first connection parts 4 cand the second connection parts 5 a of an elongated shape in the solarcell element 10A are respectively replaced with an array of a pluralityof (five in FIG. 5A) first connection parts 4 c and second connectionparts 5 a having a smaller size than those in the first embodiment inthe longitudinal direction. The formation mode of the power collectingpart 5 b is similar to that in the solar cell element 10A according tothe first embodiment.

On the other hand, as shown in FIG. 5B, the through holes 3 (conductionparts 4 b) are formed so as to substantially coincide with the formationpositions of the first connection parts 4 c in plan view, and the mainelectrode parts 4 a are uniformly formed on the first surface 1F as aplurality of linear patterns connecting with the plurality of (three inFIG. 5B) conduction parts 4 b belonging to different arrays.

When forming a solar cell module using the plurality of solar cellelements 10B, the adjacent solar cell elements 10B are arranged at apredetermined distance so that the respective base sides BS arepositioned on the same straight line and so as to be in atranslationally symmetric relationship, similar to the solar cell module20A according to the first embodiment, besides in this case, they arearranged such that the column including the plurality of firstconnection parts 4 c and the column including the plurality of secondconnection parts 5 a are positioned on the same straight line parallelto the direction of the arrow AR2. In this manner, all the firstconnection parts 4 c and all the second connection parts 5 a positionedon the same straight line are connected with one wiring 11 as in thefirst embodiment. In other words, in the present embodiment as well, therelative arrangement relationship among the sets of the first connectionparts 4 c and the second connection parts 5 a in a relation of beingconnected with one wiring 11 is equivalent (i.e., all the sets of firstconnection parts 4 c and second connection parts 5 a are in atranslationally symmetric relationship), and thus the wiring 11 of thesame shape can be used for the connection of each set of firstconnection part 4 c and the second connection part 5 a. For instance,the wiring having a shape similar to that used in the solar cell module20A can be used. The relationship of the column including the pluralityof first connection parts 4 c and the column including the plurality ofsecond connection parts 5 a is substantially the same as therelationship between the first connection part 4 c of the first solarcell element 10Aα and the second connection part 6 a of the second solarcell element 10Aβ in the solar cell module 20A according to the firstembodiment.

Regarding the solar cell element 10B, the first connection parts 4 c andthe second connection parts 5 a may be formed into a shape differentfrom above (e.g., trapezoid, circle, ellipse, semicircle, fan-shape, orcomposite shape thereof) as long as the above array state is met and theconnection mode by the wirings 11 can be realized.

Third Embodiment

A solar cell element 10C and a solar cell element 10C′, which is avariation thereof, according to a third embodiment of the presentinvention will be described with reference to FIGS. 6A to 6D and FIGS.7A and 7B.

FIGS. 6A to 6D are plan views of the solar cell element 10C and thesolar cell element 10C′ showing one example of electrode patterns of thefirst electrode 4 and the second electrode 5 in the solar cell element10C and the solar cell element 10C′. FIG. 6A is a diagram showing thesolar cell element 10C when seen in plan view from the second surface 1Sside, and FIG. 6B is a diagram showing the solar cell element 10C whenseen in plan view from the first surface side. FIG. 6C is a diagramshowing the solar cell element 10C′ when seen in plan view from thesecond surface 1S side, and FIG. 6D is a diagram showing the solar cellelement 10C′ when seen in plan view from the first surface side.

As shown in FIG. 6A, a plurality of (three in FIG. 6A) of firstconnection parts 4 c is arranged in the solar cell element 10C. Eachfirst connection part 4 c has a portion A and a portion B parallel tothe base side BS but has a folding (bent) structure in plan view. Aplurality of (three in FIG. 6A) second connection parts 5 a is alsoarranged. The second connections part 5 a are formed so as to be on thesame straight lines as the portions A of the first connection parts 4 cand so as to be parallel to the portions B of the second connectionparts 5 a. In the present embodiment as well, the power collecting part5 b is formed over substantially the entire surface other than theformation region of the first connection parts 4 c and the non-formationregion RE.

In the solar cell element 10C′ shown in FIG. 6C, the portions A of thefirst connection parts 4 c and the second connection parts 5 a eachmonolithically formed in the solar cell element 10C are respectivelyreplaced with the portions C of the first connection parts 4 c having adiscontinuous shape and the arrays of the second connection parts 5 adividing into a plurality of pieces (three in FIG. 6C). The shape of theportions D of the first connection parts 4 c are the same as the shapeof the portions B of the first connection parts 4 c of the solar cellelement 10C.

In the case where the first connection parts 4 c are arranged such thatthe lengths in the longitudinal direction (coincide with the referencedirection) of the portions A and the portions C of the first connectionparts 4 c shown in FIGS. 6A and 6C are approximately greater than orequal to 30% and less than or equal to 70% of the length of the baseside BS, the contact area of the wirings 11 and the first connectionparts 4 c can be increased. The resistance loss can be furthersuppressed through such connection.

Meanwhile, as shown in FIGS. 6B and 6D, the through holes 3 (conductionparts 4 b) are formed so as to substantially coincide with the formationpositions of the first connection parts 4 c in plan view, and the mainelectrode parts 4 a are uniformly formed on the first surface 1F as aplurality of linear patterns connecting to the plurality of (three inFIGS. 6B and 6D) conduction parts 4 b belonging to different arrays inboth the solar cell element 10C and the solar cell element 10C′.

FIGS. 7A and 7B are diagrams showing the detail of connection by thewirings 11 of the solar cell elements 10C in the solar cell module 20Cconfigured using the plurality of solar cell elements 10C. FIG. 7A is adiagram of two solar cell elements 10C adjacent to each other in thesolar cell module 20C when seen from the second surface 1S side in planview, and FIG. 7B is a diagram of the same when seen from the firstsurface 1F side in plan view. FIG. 8A is a schematic view of the entiresolar cell module 20C when seen from the first surface 1F side in planview. In FIG. 7A, the solar cell elements 10C configuring the solar cellmodule 20C are not the same as those shown in FIGS. 6A to 6D, and are ina mirror symmetric relationship (line symmetric with respect to thecenter line of the solar cell element 10C), but the description of thepresent embodiment is established in using either solar cell element 10Cin a symmetric relationship as long as the same solar cell elements 10Care used when configuring one solar cell module 20C.

In the case where the solar cell module 20C is configured using thesolar cell element 10C in which the first connection parts 4 c and thesecond connection parts 5 a have the shape and the arrangementrelationship described above, the portion A of the first connection part4 c of one solar cell element 10C and the second connection part 5 a ofthe other solar cell element 10C exist on one straight line if theadjacent solar cell elements 10C are arranged so that the respectivebase sides BS are positioned on the same straight line and are in atranslationally symmetric relationship, as shown in FIG. 7A. Regardingthe solar cell module 20C, the portion A of the first connection part 4c and the second connection part 5 a satisfying such a relationship areconnected using the wiring 11 having a linear shape in plan view. In thepresent embodiment as well, the relative arrangement relationship amongthe sets of the first connection part 4 c and the second connection part5 a in a relationship of being connected with one wiring 11 isequivalent (i.e., all the sets of the first connection part 4 c and thesecond connection part 5 a are in a translationally symmetricrelationship), and thus the wiring 11 having the same shape can be usedin the connection of each set of first connection part 4 c and thesecond connection part 5 a. The wiring having a shape similar to thatused in the solar cell module 20A can be used, for example.

In the case of forming a solar cell module using a plurality of solarcell elements 10C′, the adjacent solar cell elements 10C′ are arrangedat a predetermined distance so that the respective base sides BS arepositioned on the same straight line and so as to be in atranslationally symmetric relationship, as in the solar cell module 20C.Thus, the portion C of the first connection part 4 c and all the secondconnection parts 5 a positioned on the same straight line are connectedwith one wiring 11. In this case also, the relative arrangementrelationship among the sets of the first connection part 4 c and thesecond connection part 5 a in a relation of being connected with onewiring 11 is equivalent (i.e., all the sets of first connection part 4 cand second connection part 5 a are in a translationally symmetricrelationship), and thus the wiring 11 of the same shape can be used forthe connection of each set of portion C of the first connection part 4 cand the second connection part 5 a. For instance, the wiring having ashape similar to that used in the solar cell module 20A can be used.

Regarding the solar cell element 10C′, the portion C and the secondconnection part 5 a may be formed into a shape different from above(e.g., trapezoid, circle, ellipse, semicircle, fan-shape, or compositeshape thereof as long as the above array state is met and the connectionmode by the wiring 11 can be realized.

FIGS. 9A and 9B are diagrams showing a solar cell element 10C″, which isanother variation of the solar cell element 10C, and a solar cell module20C″ configured using a plurality of solar cell elements 10C″ accordingto the present embodiment. FIG. 9A is a diagram of the solar cellelement 10C″ when seen from the second surface 1S side in plan view, andFIG. 9B is a diagram of two adjacent solar cell elements 10C″ in thesolar cell module 20C″ when seen from the second surface 1S side in planview.

The solar cell element 10C″ is similar to the solar cell element 10C inthat the first connection part 4 c has a bent shape, but differs fromthe solar cell element 10C in that the second connection part 5 a alsohas a bent shape. However, in the solar cell module 20C″ configuredusing the solar cell element 10C″ as well, a state in which the firstconnection part 4 c of one solar cell element 10C″ and the secondconnection part 5 a of the other solar cell element 10C exist on onestraight line is realized by arranging the adjacent solar cell elements10C″ so that the respective base sided BS are positioned on the samestraight line and are in a translationally symmetric relationship, asshown in FIG. 9B. The solar cell module 20C″ is also similar to thesolar cell module 20C in that the first connection part 4 c and thesecond connection part 5 a lined on one straight line are connectedusing a wiring 11 in a linear form in plan view.

Fourth Embodiment

A solar cell element 10D and a solar cell element 10D′, which is avariation thereof, according to a fourth embodiment, will be describedwith reference to FIGS. 10A to 10D and FIGS. 11A and 11B.

FIGS. 10A to 10D are plan views of the solar cell element 10D and thesolar cell element 10D′ showing one example of electrode patterns of thefirst electrode 4 and the second electrode 5 in the solar cell element10D and the solar cell element 10D′. FIG. 10A is a diagram showing thesolar cell element 10D when seen from the second surface 1S side in planview, and FIG. 10B is a diagram showing the solar cell element 10D whenseen from the first surface side 1F in plan view. FIG. 10C is a diagramshowing the solar element 10D′ when seen from the second surface 1S sidein plan view, and FIG. 10D is a diagram showing the solar cell element10D′ when seen from the first surface 1F side in plan view.

As shown in FIG. 10A, a plurality of (four in FIG. 10A) first connectionparts 4 c is arranged in the solar cell element 10D. Each firstconnection part 4 c has an elongated shape (rectangle) parallel to thebase side BS and is arranged at substantially regular intervals parallelto the reference direction. On the other hand, the second connectionparts 5 a of the same number as the first connection parts 4 c are alsoarranged. Each second connection part 5 a also has an elongated shape(rectangle) parallel to the base side BS and is arranged atsubstantially regular intervals parallel to the reference direction. Thefirst connection parts 4 c and the second connection parts 5 a arealternately arranged. Furthermore, the first connection parts 4 c andthe second connection parts 5 a in the solar cell element 10D have therespective arrangement positions defined so that a rotationallysymmetrical arrangement is realized between adjacent solar cell elements10D when configuring a solar cell module 20D, as will be describedlater.

In the present embodiment, an elongated power collecting part 5 b isformed at the peripheries of the second connection parts 5 a. Thus, thenon-formation region RE is ensured near both the ends of the firstconnection parts 4 c. This aspect will be described later.

In the solar cell element 10D′ shown in FIG. 10C, both the plurality offirst connection parts 4 c and the plurality of second connection parts5 a, each of them having a rectangular shape, are arranged atsubstantially regular intervals and discretely at positions where thefirst connection parts 4 c and the second connection parts 5 a areformed in the solar cell element 10D. That is, the solar cell element10D′ has a configuration in which the first connection parts 4 c and thesecond connection parts 5 a having an elongated shape in the solar cellelement 10D are replaced with arrays of the plurality of (five in FIG.10C) first connection parts 4 c and second connection parts 5 a havingsmaller sizes than those in the solar cell element 10D in thelongitudinal direction. The formation mode of the power collecting part5 b is similar to that in the solar cell element 10D.

On the other hand, as shown in FIGS. 10B and 10D, in both the solar cellelement 10D and the solar cell element 10D′, the through holes 3(conduction parts 4 b) are formed so as to substantially coincide withthe formation positions of the first connection parts 4 c in plan view,and the main electrode parts 4 a are uniformly formed on the firstsurface 1F as a plurality of linear patterns connecting with theplurality of (four in FIGS. 10B and 10D) conduction parts 4 b belongingto different arrays.

FIGS. 11A and 11B are diagrams showing the detail of connection of thesolar cell elements 10D by the wirings 11 in the solar cell module 20Dconfigured using the plurality of solar cell elements 10D. FIG. 11A is adiagram of two solar cell elements 10D adjacent to each other in thesolar cell module 20D seen in plan view from the side of the secondsurface 1S. FIG. 11B is a diagram of the same in plan view seen from theside of the first surface 1F. FIG. 8B is a schematic view of the entiresolar cell module 20D when seen from the first surface 1F side in planview.

In the case of configuring the solar cell module 20D using the solarcell element 10D in which the first connection parts 4 c and the secondconnection parts 5 a have the shape and the arrangement relationship asdescribed above, the first connection part 4 c of one solar cell element10D and the second connection part 5 a of the other solar cell element10D exist on one straight line if the adjacent solar cell elements 10Dare arranged so that the respective base sides BS are parallel and areat positions not on the same straight line, and are in a rotationallysymmetric (more specifically, point symmetric) relationship. In the caseshown in FIGS. 11A and 11B, point Q is the center of rotationalsymmetry. In the solar cell module 20D, the first connection parts 4 cand the second connection parts 5 a satisfying such a relationship areconnected using the wirings 11 in a linear form in plan view. In thepresent embodiment also, the mutual relative arrangement relationshipamong the sets of the first connection part 4 c and the secondconnection part 5 a in a relationship of being connected with one wiring11 is equivalent (i.e., the sets of the first connection part 4 c andthe second connection part 5 a are all in a translationally symmetricrelationship), and thus the wiring 11 having the same shape can be usedfor the connection of each set of the first connection part 4 c and thesecond connection part 5 a. The wiring 11 having a shape similar to thatused in the solar cell module 20A can be used, for example.

The non-formation region RE is ensured near both the ends of the firstconnection parts 4 c in the solar cell element 10D as described above inorder to adapt to circumstances where there are two directions eachsolar cell element 10D may take in the solar cell module 20D and theconnecting position by the wiring 11 differs according to thedirections, namely, in order to use the solar cell elements 10D havingthe same electrode patterns regardless of the directions.

On the other hand, in the case of forming a solar cell module using aplurality of solar cell elements 10D′, the adjacent solar cells 10D′ arearranged so that the respective base sides BS are parallel and are notat positions on the same straight line and so that they are in arotationally symmetric (specifically, point symmetric) relationship witheach other, as in the solar cell module 20D. Accordingly, all the firstconnection parts 4 c and all the second connection parts 5 a positionedon the same straight line are connected by one wiring 11. In this case,the relative arrangement relationship among the sets of the plurality offirst connection parts 4 c and the plurality of second connection parts5 a in a relationship of being connected with one wiring 11 isequivalent (i.e., the sets of the plurality of first connection parts 4c and the plurality of second connection parts 5 a are all in atranslationally symmetric relationship), and thus the wiring 11 havingthe same shape can be used for the connection of each set of the firstconnection part 4 c and the second connection part 5 a.

Regarding the solar cell element 10D′, the first connection parts 4 cand the second connection parts 5 a may be formed into a shape differentfrom above (e.g., trapezoid, circle, ellipse, semicircle, fan-shape, orcomposite shape thereof) as long as the above array state is met and theconnection mode by the wiring 11 can be realized.

The power collecting amount of the first connection parts 4 c and thesecond connection parts 5 a is smaller at the ends of the semiconductorsubstrate 1 than at the central part, and thus the formation widths inthe short direction of the first connection parts 4 c and the secondconnection parts 5 a at the ends may be shorter than at the centralpart.

Fifth Embodiment

The solar cell element 10E according to a fifth embodiment of thepresent invention will be described with reference to FIGS. 12A and 12Band FIGS. 13A and 13B.

FIGS. 12A and 12B are plan views of the solar cell element 10E showingone example of electrode patterns of the first electrode 4 and thesecond electrode 5 in the solar cell element 10E. FIG. 12A is a diagramof the solar cell element 10E when seen from the second surface 1S side,and FIG. 12B is a diagram of the solar cell element 10E when seen fromthe first surface side in plan view.

As shown in FIG. 12A, in the solar cell element 10E, each firstconnection part 4 c having a rectangular shape and having a longitudinaldirection in the reference direction are divided into plural pieces intoa plurality of columns (three columns in FIG. 12A) and is arranged witha gap at substantially the regular intervals (five in FIG. 12A). Thecolumns are arranged at substantially equal intervals parallel to thereference direction. On the other hands, each plurality of (four in FIG.12A) second connection parts 5 a having a rectangular shape and having alongitudinal direction in the reference direction is arranged, with agap at substantially the regular intervals, in a plurality of columns(i.e., the number of columns is the same as that of the columns of thefirst connection parts 4 c) along the columns of the first connectionparts 4 c.

More specifically, the first connection parts 4 c and the secondconnection parts 5 a are arranged to satisfy the relationship that thereexists at least partially adjacent second connection part 5 a for allthe clearances between the first connection parts 4 c. For example, thesecond connection part 5 a 1 is adjacent to a part of the clearance s1,and the second connection part 5 a 2 is adjacent to the entire clearances2. When the first connection parts 4 c and the second connection parts5 a are arranged in such an arrangement relationship, the number ofsecond connection parts 5 a becomes less than the number of firstconnection parts 4 c (thus the size in the longitudinal directionbecomes large), but the second connection parts 5 a may be arranged inthe same as or in a greater number than the first connection parts 4 c.One elongated second connection part 5 a can be arranged instead ofbeing arranged in plurals. Furthermore, in the case of forming the highconcentration doped layer 6 through the formation of the powercollecting part 5 b, a larger power collecting part 5 b (highconcentration doped layer 6) can be formed in the clearances between thesecond connection parts 5 a by arranging a great number of secondconnection parts 5 a, whereby the output characteristic of the solarcell element 10E can be enhanced.

Furthermore, in the solar cell element 10E, the arrangement positions ofthe first connection parts 4 c and the second connection parts 5 a aredefined so that a rotationally symmetric arrangement is realized betweenthe adjacent solar cell elements 10E in the case of configuring a solarcell module 20E, as will be described later.

In the solar cell element 10E as wells the power collecting part 5 b isformed over substantially the entire surface other than the formationregion of the first connection parts 4 c, as in the other embodiments.However, in the case of the solar cell element 10E, enlargement of theformation region of the power collecting part 5 b and enlargement in theformation region of the high concentration doped layer 6 are achieved bytwo aspects in that both the first connection parts 4 c and the secondconnection parts 5 a are arranged up to the vicinity of the ends of thesemiconductor substrate 1 in the arraying direction and thenon-formation region RE is not ensured, and in that the power collectingpart 5 b is formed even at the clearance portions between the firstconnection parts 4 c arranged in the same columns parallel to the baseside BS.

In the solar cell element 10E having such an arrangement relationship,the carriers collected by the power collecting part 5 b in the region onthe side opposite to the columns of the second connection parts 5 a withrespect to the columns of the first connection parts 4 c parallel to thebase side BS can be satisfactorily retrieved from the second connectionparts 5 a. Particularly in the case shown in FIG. 12A, the powercollection from the region F not formed with the second connection parts5 a is effectively carried out. That is, satisfactory power collectingefficiency can be obtained without arranging the second connection parts5 a in the region F.

On the other hand, as shown in FIG. 12B, the through holes 3 (conductionparts 4 b) are formed so as to substantially coincide with the formationpositions of the first connection parts 4 c in plan view in the solarcell element 10E. In the solar cell element 10E, two through holes 3(conduction parts 4 b) are formed in correspondence to one firstconnection part 4 c. Furthermore, the main electrode parts 4 a areuniformly formed on the first surface 1F as a plurality of linearpatterns connecting to all the conduction parts 4 b. The main electrodeparts 4 a arranged perpendicular to the connecting direction of thewirings 11 may be arranged only at the portions where the clearancesbetween the conduction parts 4 b are large.

FIGS. 13A and 13B are diagrams showing the detail of connection by thewirings 11 of the solar cell elements 10E in the solar cell module 20Econfigured using a plurality of solar cell elements 10E. FIG. 13A is adiagram of two solar cell elements 10E adjacent to each other in thesolar cell module 20E when seen from the second surface 1S side in planview, and FIG. 13B is a diagram of the same when seen from the firstsurface 1F side in plan view.

In the case of configuring the solar cell module 20E using the solarcell element 10E described above, the adjacent solar cell elements 10Eare arranged so that the respective base sides BS are parallel and arenot positioned on the same straight line, and are in a rotationallysymmetric (specifically, point symmetric) relationship with each other,as shown in FIG. 13A, as in the solar cell module 20D. According to suchan arrangement, the first connection parts 4 c of one solar cell element10E and the second connection parts 5 a of the other solar cell element10E exist on one straight line. In the solar cell module 20E, such firstconnection parts 4 c and second connection parts 5 a are connected usingthe wirings 11 having a linear form in plan view. In the presentembodiment as well, the relative arrangement relationship among the setsof the first connection parts 4 c and the second connection parts 5 a ina relationship of being connected with one wiring 11 is equivalent(i.e., all the sets of the first connection parts 4 c and the secondconnection parts 5 a are in a translationally symmetric relationship).Therefore, the connection of each set of the first connection part 4 cand the second connection part 5 a is performed by the wiring 11 havingthe same shape. For instance, the wiring having a shape similar to thatused in the solar cell module 20A may be used.

If the wiring 11 connected to the first connection parts 4 c of thesolar cell element 10E contacts the power collecting part 5 b of thesame solar cell element 10E, the first connection parts 4 c and thepower collecting part 5 b short-circuit and leakage occurs. Thus, aninsulating layer is preferably formed on the power collecting part 5 bat the locations that it might contact the wirings 11. Alternatively,connection may be made using a wiring similar to a wiring 11B having aplurality of bent parts in cross-sectional view as will be describedlater.

Regarding the solar cell element 10E, the first connection parts 4 c andthe second connection parts 5 a may be formed into a shape differentfrom above (e.g., trapezoid, circle, ellipse, semicircle, fan-shape, orcomposite shape thereof) as long as the above array state is met and theconnection mode by the wiring 11 can be realized.

Sixth Embodiment

A solar cell element 10F according to a sixth embodiment of the presentinvention will be described with reference to FIGS. 14A and 14B andFIGS. 15A and 15B.

FIGS. 14A and 14B are plan views of the solar cell element 10F showingone example of electrode patterns of the first electrode 4 and thesecond electrode 5 in the solar cell element 10F. FIG. 14A is a diagramof the solar cell element 10F when seen from the second surface 1S sidein plan view, and FIG. 14B is a diagram of the solar cell element 10Fwhen seen from the first surface 1F side in plan view.

As shown in FIG. 14A, in the solar cell element 10F, each plurality of(four in FIG. 14A) first connection parts 4 c having a rectangular shapeand having a longitudinal direction in the reference direction isdivided into a plurality of columns (six columns in FIG. 14A) and isarranged with a gap at substantially the regular intervals. Each columnis arranged at substantially the regular intervals parallel to thereference direction. On the other hand, each plurality of (four in FIG.14A) second connection parts 5 a having a rectangular shape and having alongitudinal direction in the reference direction, similar to the firstconnection parts 4 c, is arranged with a gap at substantially theregular intervals in a plurality of columns along the columns of thefirst connection parts 4 c (i.e., the number of columns is the same asthat of the columns of the first connection parts 4 c).

More specifically, the columns of the first connection parts 4 c and thecolumns of the second connection parts 5 a configure a plurality of sets(three sets in FIG. 14A) arranged alternately and adjacent to oneanother by a plurality of columns (two columns in FIG. 14A). From thearrangement relationship with the columns of the second connection parts5 a, the columns of the first connection parts 4 c are distinguishedbetween a first column 4 ca in which the column of the second connectionparts 5 a exists only on one side and a second column 4 cb in which thecolumn of the second connection parts 5 a exists on both sides(sandwiched between the columns of the second connection parts 5 a).Further, the adjacent columns of the first connection parts 4 cbelonging to the same set (e.g., the first column 4 ca and the secondcolumn 4 cb in FIG. 14A) are arranged such that the arrangementrelationship between the first connection parts 4 c and the clearancesin the reference direction is reversed from each other between theadjacent columns.

Similarly, the adjacent columns of the second connection parts 5 abelonging to the same set (e.g., the two columns on both sides of thesecond column 4 cb in FIG. 14A) are arranged such that the arrangementrelationship between the second connection parts 5 a and the clearancesin the reference direction is reversed from each other between theadjacent columns, and the second connection parts 5 a are adjacent tothe first connection parts 4 c configuring the second column 4 cb.

Furthermore, in the solar cell element 10F, the arrangement positions ofthe first connection parts 4 c and the second connection parts 5 a aredefined so that a rotationally symmetric arrangement is realized betweenthe adjacent solar cell elements 10F in the case of configuring a solarcell module 20F, as will be described later.

In the solar cell element 10F as well, the power collecting part 5 b isformed over substantially the entire surface other than the formationregion of the first connection parts 4 c, as in the other embodiments.However, in the case of the solar cell element 10F, the non-formationregion RE is not prepared, and the power collecting part 5 b is formedeven in the clearance portions of the first connection parts 4 carranged in the same column. That is, enlargement of the formationregion of the power collecting part 5 b and enlargement in the formationregion of the high concentration doped layer 6 are achieved.

On the other hand, as shown in FIG. 14B, the through holes 3 (conductionparts 4 b) are formed so as to substantially coincide with the formationpositions of the first connection parts 4 c in plan view in the solarcell element 10F. In the solar cell element 10F, two through holes 3(conduction parts 4 b) are formed in correspondence to one firstconnection part 4 c. Furthermore, the main electrode parts 4 a areuniformly formed on the first surface 1F as a plurality of linearpatterns connecting to the plurality of (three in FIG. 14B) conductionparts 4 b belonging to different arrays.

FIGS. 15A and 15B are diagrams showing the detail of connection by thewirings 11 of the solar cell elements 10F in the solar cell module 20Fconfigured using a plurality of solar cell elements 10F. FIG. 15S is adiagram of two solar cell elements 10F adjacent to each other in thesolar cell module 20F when seen from the second surface 1S side in planview, and FIG. 15B is a diagram of the same when seen from the firstsurface 1F side in plan view.

In the case of configuring the solar cell module 20F using the solarcell element 10F as described above, the adjacent solar cell elements10P are arranged so that the respective base sides BS are parallel andare at positions not on the same straight line, and are in arotationally symmetric (specifically, point symmetric) relationship witheach other, as shown in FIG. 15A, as in the solar cell module 20D.According to such an arrangement, the first connection parts 4 c of onesolar cell element 10F and the second connection parts 5 a of the othersolar cell element 10F exist on one straight line. In the solar cellmodule 20F, such first connection parts 4 c and second connection parts5 a are connected using the wiring 11 having a linear form in plan view.In the present embodiment as well, the relative arrangement relationshipamong the sets of the first connection parts 4 c and the secondconnection parts 5 a in a relationship of being connected with onewiring 11 is equivalent (i.e., all the sets of the first connectionparts 4 c and the second connection parts 5 a are in a translationallysymmetric relationship), and thus the connection of each set of thefirst connection part 4 c and the second connection part 5 a isperformed by the wiring 11 having the same shape. For instance, a wiringhaving a shape similar to that used in the solar cell module 20A may beused.

Since the number of wirings 11 in the solar cell module 20F shown inFIGS. 15S and 15B is greater than those of the solar cell modules shownin the embodiments above, resistance loss that occurs when current flowsconcentrating on one wiring 11 is less likely to occur.

If the wirings 11 connected to the first connection parts 4 c of thesolar cell element 10F contacts the power collecting part 5 b of thesame solar cell element 10, the first connection parts 4 c and the powercollecting part 5 b short-circuit and leakage occurs, and thus, aninsulating layer (not shown) is preferably formed on the powercollecting part 5 b at the locations that it might contact the wirings11. Alternatively, the connection may be made using a wiring similar tothe wiring 11B having a broken line shape in cross-sectional view aswill be described later.

Also, regarding the solar cell element 10F, the first connection parts 4c and the second connection parts 5 a may be formed into a shapedifferent from above (e.g., trapezoid, circle, ellipse, semicircle,fan-shape, or composite shape thereof as long as the above array stateis met and the connection mode by the wiring 11 can be realized.

Seventh Embodiment

A solar cell element 10G according to a seventh embodiment of thepresent invention and a solar cell element 10G′, which is a variationthereof, will be described with reference to FIGS. 16A to 16D and FIGS.17A and 17B.

FIGS. 16A to 16D are plan views of the solar cell element 10G and thesolar cell element 10G′ showing one example of electrode patterns of thefirst electrode 4 and the second electrode 5 in the solar cell element10G and the solar cell element 10G′. FIG. 16A is a diagram of the solarcell element 10G when seen from the second surface 1S side in plan view,and FIG. 16B is a diagram of the solar cell element 10G when seen fromthe first surface 1F side in plan view. FIG. 16C is a diagram of thesolar cell element 10G′ when seen from the second surface 1S side inplan view, and FIG. 16D is a diagram of the solar cell element 10G′ whenseen from the first surface 1F side in plan view.

The shapes and the arrangement relationships of the first connectionparts 4 c and the second connection parts 5 a in the solar cell element10G and the solar cell element 10G′ shown in FIGS. 16A and 16C aresimilar to the first connection parts 4 c and the second connectionparts 5 a of the solar cell element 10D according to the fourthembodiment in that the longitudinal direction is in the referencedirection and both the parts are arranged in parallel to the referencedirection and alternately. However, the solar cell element 10G and thesolar cell element 10G′ differ from the solar cell element 10D in therelationship in the numbers of the first connection parts 4 c and thesecond connection parts 5 a.

That is, as shown in FIG. 16A, n (n is a natural number) pieces of firstconnection parts 4 c and n−1 pieces second connection parts 5 a arearranged in the solar cell element 10G. In FIG. 16A, a case of n=4 isshown. Meanwhile, as shown in FIG. 16C, n−1 pieces of first connectionparts 4 c and n pieces of second connection parts 5 a are arranged inthe solar cell element 10G′. In FIG. 16C, a case of n=4 is shown.

As shown in FIGS. 16B and 16D, the through holes 3 (conduction parts 4b) are formed so as to substantially coincide with the formationpositions of the first connection parts 4 c in plan view, and the mainelectrode parts 4 a are uniformly formed on the first surface 1F as aplurality of linear patterns connecting to the plurality of (four inFIG. 16B, three in FIG. 16D) conduction parts 4 b belonging to differentarrays both in the solar cell element 10G and the solar cell element10G′.

FIGS. 17A and 17BG are diagrams showing the detail of connection by thewirings 11 of the solar cell elements 10G and the solar cell elements10G′ in the solar cell module 20G configured using a plurality of solarcell elements 10G and a plurality of solar cell elements 10G′. FIG. 17Ais a diagram of the solar cell element 10G and the solar cell element10G′ adjacent to each other in the solar cell module 20G when seen fromthe second surface 1S side in plan view, and FIG. 17B is a diagram ofthe same when seen from the first surface 1F side in plan view.

The solar cell module 20G differs from the solar cell module accordingto each embodiment described above, and the solar cell element 10G andthe solar cell element 10G′ having different arrangement relationshipsbetween the first connection parts 4 c and the second connection parts 5a are arranged alternately and so that the respective base sides BS arepositioned on one straight line. In the solar cell module 20G havingsuch a configuration, the first connection parts 4 c of a certain solarcell element 10G and the second connection parts 5 a of the adjacentlypositioned solar cell element 10G′ exist on one straight line. In thesolar cell module 20G, the first connection parts 4 c and the secondconnection parts 5 a satisfying such a relationship are connected usingthe wirings 11 (first wiring, second wiring) having a linear form inplan view. In the present embodiment as well, the relative arrangementrelationship among the sets of the first connection part 4 c and thesecond connection part 5 a in a relationship of being connected with onewiring 11 is equivalent (i.e., all the sets of the first connection part4 c and the second connection part 5 a are in a translationallysymmetric relationship), and thus the connection of each set of thefirst connection part 4 c and the second connection part 5 a isperformed by the wiring 11 having the same shape. For instance, a wiringhaving a shape similar to that used in the solar cell module 20A may beused.

Eighth Embodiment

A solar cell element 10H according to an eighth embodiment of thepresent invention will now be described with reference to FIGS. 18A and18B, FIGS. 19A and 19B, and FIGS. 20A and 20B.

FIGS. 18A and 18B are plan views of the solar cell element 10H showingone example of electrode patterns of the first electrode 4 and thesecond electrode 5 in the solar cell element 10H. FIG. 18A is a diagramof the solar cell element 10H when seen from the second surface 1S sidein plan view, and FIG. 18B is a diagram of the solar cell element 10Hwhen seen from the first surface 1F side in plan view.

As shown in FIG. 18A, in the solar cell element 10H, each plurality offirst connection parts 4 c having a square shape is arranged discretelyat substantially regular intervals in a plurality of columns (threecolumns in FIG. 18A) parallel to the reference direction, and the secondconnection parts 5 a are arranged between the first connection parts 4 cin each column. In FIG. 18A, five first connection parts 4 c and foursecond connection parts 5 a are arranged in one column. The columns arearranged at substantially regular intervals in parallel to the referencedirection. The first connection parts 4 c and the second connectionparts 5 a are formed into a size with which two wirings 11 can bearranged parallel to the reference direction when forming a solar cellmodule 20H to be described later.

Similar to other embodiments, in the solar cell element 10H, the powercollecting part 5 b is formed over substantially the entire surfaceother than the formation region of the first connection parts 4 c. Sincethe second connection parts 5 a are arranged while being sandwichedbetween the power collecting part 5 b in the solar cell element 10H, thecarriers collected at the power collecting part 5 b are efficientlygathered at the second connection parts 5 a.

As shown in FIG. 18B, in the solar cell element 10H, the through holes 3(conduction parts 4 b) are formed so as to substantially coincide withthe formation positions of the first connection parts 4 c in plan view.In the solar cell element 10H, two through holes (conduction parts 4 b)are formed in correspondence to one first connection part 4 c.Furthermore, the main electrode parts 4 a are uniformly formed on thefirst surface 1F as a plurality of linear patterns connecting to theplurality of (three in FIG. 18B) conduction parts 4 b belonging todifferent arrays.

FIGS. 19A and 19B are diagrams showing the detail of connection by thewirings 11 of the solar cell elements 10H in the solar cell module 20Hconfigured using a plurality of solar cell elements 10H. FIG. 19A is adiagram of two solar cell elements 10H adjacent to each other in thesolar cell module 20H when seen from the second surface 1S side in planview, and FIG. 19B is a diagram of the same when seen from the firstsurface 1F side in plan view.

In the case of configuring the solar cell module 20H using the solarcell element 10H in which the first connection parts 4 c and the secondconnection parts 5 a have the shapes and the arrangement relationshipdescribed above, the adjacent solar cell elements 10H are arranged sothat the respective base sides BS are parallel and are positioned on thesame straight line, and are in a translationally symmetric relationshipwith each other, as shown in FIG. 19A, as in the solar cell module 20A,whereby the first connection parts 4 c of one solar cell element 10H andthe second connection parts 5 a of the other solar cell element 10Hexist on one straight line. In the following description, of the twosolar cell elements 10H connected by the wirings 11 in FIGS. 19A and19B, the solar cell element 10H having the wirings 11 connected to thefirst connection parts 4 c is referred to as a first solar cell element10Hα, and the solar cell element 10H having the wirings connected to thesecond connection parts 5 a is referred to as a second solar cellelement 10Hβ, for the sake of convenience.

In the solar cell module 20H, the first connection parts 4 c of thefirst solar cell element 10Hα and the second connection parts 5 a of thesecond solar cell element 10Hβ satisfying the above relationship areconnected using the wirings 11 having a linear form in cross section,similar to that in the solar cell module 20A according to the firstembodiment. In this case, the first connection parts 4 c and the secondconnection parts 5 a alternately arranged in one column in one solarcell element 10H are connected to the second connection parts 5 a andthe first connection parts 4 c of a different solar cell element,respectively. That is, two wirings 11 are connected in parallel in thatcolumn.

In this case, however, when attempting to connect them as it is with thewirings 11, the first connection parts 4 c and the second connectionparts 5 a are caused to short-circuit in the first solar cell element10Hα and the second solar cell element 10Hβ. In order to avoid this, inthe present embodiment, when fabricating the solar cell element 10H orwhen configuring the solar cell module 20H, an insulating layer (notshown) made of an oxide film, resin (an epoxy resin, an acrylic resin, apolyimide resin, a silicone resin, and the like), an insulating tape,and the like is arranged on the second connection parts 5 a of the firstsolar cell element 10Hα and the first connection parts 4 c of the secondsolar cell element 10Hβ at a portion to be positioned immediately underthe wirings 11, and then connecting with the wirings 11 is carried out.More specifically, since the two wirings 11 having different connectingdestinations are connected to the column in which the first connectionparts 4 c and the second connection parts 5 a are alternatelypositioned, the insulating layer is formed only at half of the region inthe first connection parts 4 c and the second connection parts 5 a. Thatis, as for the first connection parts 4 c, the insulating layer isformed only in the region assumed as the first connection parts 4 c ofthe second solar cell element 10Hβ, and as for the second connectionparts 5 a, the insulating layer is formed only in the region assumed asthe second connection parts 5 a of the first solar cell element 10Hα.

Therefore, in the present embodiment, the relative arrangementrelationship among the sets of the first connection parts 4 c and thesecond connection parts 5 a in a relationship of being connected withone wiring 11 is equivalent (i.e., the sets of first connection parts 4c and second connection parts 5 a are all in a translationally symmetricrelationship), and thus the wiring 11 having the same shape can be usedfor the connection of each set of the first connection part 4 c and thesecond connection part 5 a.

The formation of the insulating layer may be a mode of being performedby patterning through an application method or the like so as to beformed only at the relevant locations, or a mode of removing unnecessaryportions after performing film formation with an insulating layerformation material on the second surface 1S side of the semiconductorsubstrate 1 after the first connection parts 4 c, the second connectionparts 5 a, and the power collecting parts 5 b are formed.

FIG. 20A is a schematic view of a cross section parallel to thereference direction of the two solar cell elements 10H adjacent to eachother in the solar cell module 20H to describe another connection modein the solar cell module 20H. FIG. 20B is a perspective view showing astate of connection in such a connection mode.

In this mode, the first connection parts 4 c of the first solar cellelement 10Hα and the second connection parts 5 a of the second solarcell element 10Hβ are connected using wirings 11B having a plurality ofbent parts in cross-sectional view, as shown in FIGS. 20A and 20B. Awiring in which a copper film covered with solder similar to that usedin the wiring 11 is folded in an appropriate shape is used for thewiring 11.

The wiring 11B has a plurality of first connection surfaces 11 aconnecting with the first connection parts 4 c at the first solar cellelement 10Hα, a first separated part 11 b between two first connectionsurfaces 11 a, a plurality of second connection surfaces 11 c connectingwith the second connection parts 5 a at the second solar cell element10Hβ, and a second separated part 11 d between two second connectionsurfaces 11 c. When the first connection surfaces 11 a of the wiring 11Bare connected to the first connection parts 4 c of the first solar cellelement 10Hα and the second connection surfaces 11 c of the wiring 11Bare connected to the second connection parts 5 a of the second solarcell element 10Hβ while the plurality of solar cell elements 10Harranged as described above, a gap G1 exists between the secondconnection part 5 a of the first solar cell element 10Hα and the firstseparated part 11 b of the wiring 11B. Similarly, a gap G2 existsbetween the first connection part 4 c of the second solar cell element10Hβ and the second separated part 11 d of the wiring 11B. The shortcircuit between the first connection parts 4 c and the second connectionparts 5 a in one solar cell element 10H is reduced by having the gapsG1, G2 acting similarly to the insulating layer in the case of using thewiring 11 having a linear form in cross section as shown in FIGS. 19Aand 19B. A mode of arranging the insulating layer (not shown) forfilling the gaps G1, G2 on the wiring 11B in advance, and connecting thewiring 11B may be adopted.

In the case of performing connection using such a wiring 11B, thequality of alignment of the wiring 11B and the first connection parts 4c and the second connection parts 5 a can be visibly checked. Thereduction in connection failure can thereby be achieved.

Since the relative arrangement relationship among the sets of the firstconnection parts 4 c and the second connection parts 5 a to be connectedis still equivalent even in the case of using the wiring 11B, a wiringhaving the same shape can be used for the wiring 11B used in connectingeach set of the first connection part 4 c and the second connection part5 a.

Furthermore, in the solar cell element 10H, the first connection parts 4c and the second connection parts 5 a may be formed into a shapedifferent from above (e.g., trapezoid, circle, ellipse, semicircle,fan-shape, or composite shape thereof) as long as the above array stateis met and the connection mode by the wiring 11 can be realized.

Ninth Embodiment

A solar cell element 10I according to a ninth embodiment of the presentinvention will be described with reference to FIGS. 21A and 21B andFIGS. 22A and 22B.

FIGS. 21A and 21B are plan views of the solar cell element 10I showingone example of electrode patterns of the first electrode 4 and thesecond electrode 5 in the solar cell element 10I. FIG. 21A is a diagramof the solar cell element 10I when seen from the second surface 1S sidein plan view, and FIG. 21B is a diagram of the solar cell element 10Hwhen seen from the first surface 1F side in plan view.

As shown in FIG. 21A, in the solar cell element 10I, each plurality of(five in the FIG. 21A) first connection parts 4 c having a rectangularshape and having a longitudinal direction in the reference direction isarranged with a gap at substantially regular intervals in a plurality ofcolumns (three columns in FIG. 21A), as in the solar cell element 10Eaccording to the fifth embodiment. The columns are arranged atsubstantially regular intervals in parallel to the reference direction.Meanwhile, each plurality of (four in the FIG. 21A) second connectionparts 5 a having a rectangular shape and having a longitudinal directionin the reference direction is arranged with a gap formed atsubstantially regular intervals in a plurality of columns (i.e., thenumber of columns is the same as that of the columns of the firstconnection parts 4 c) along the columns of the first connection parts 4c.

The solar cell element 10I is the same as the solar cell element 10E ofthe fifth embodiment in that the arrangement positions of the firstconnection parts 4 c and the second connection parts 5 a are defined sothat a rotationally symmetric arrangement is realized between solar cellelements 10I adjacent to each other in the case a solar cell module 20Ito be described later is configured with them.

Furthermore, the solar cell element 10I is the same as the solar cellelement 10E in that the first connection parts 4 c and the secondconnection parts 5 a are arranged so as to satisfy a relationship thatthere exits at least partially adjacent second connection part 5 a forall the clearances between the first connection parts 4 c, and theformation mode of the power collecting part 5 b is also similar to thesolar cell element 10E.

Furthermore, as shown in FIG. 21B, the formation mode of the throughholes 3 (conduction parts 4 b) is also similar.

However, the solar cell element 10I differs from the solar cell element10E according to the fifth embodiment in three aspects that the solarcell element 10I has the columns of the first connection parts 4 c andthe columns of the second connection parts 5 a spaced apart, that eachfirst connection part 4 c includes a region 4 c 1 where the wiring isarranged and a region 4 c 2 connected with the through hole and isformed into a convex shape in plan view having the latter region as aconvex part, and that the through holes 3 are formed only immediatelyabove the through hole arrangement regions 4 c 2 of the first connectionparts 4 c and not formed immediately above the wiring arrangementregions 4 c 1.

FIGS. 22A and 22B are diagrams showing the detail of connection by thewirings 11 between the solar cell elements 10I in the solar cell module20I configured using a plurality of solar cell elements 10I having theabove configuration. FIG. 22A is a diagram of two solar cell elements10I adjacent to each other in the solar cell module 20I when seen fromthe second surface 1S side in plan view, and FIG. 22B is a diagram ofthe same when seen from the first surface 1F side in plan view.

In the case of configuring the solar cell module 20I using the solarcell element 10I as described above, the adjacent solar cell elements10E are arranged so that that the respective base sides BS are paralleland are positioned not on the same straight line, and are in arotationally symmetric (more specifically, point symmetric) relationshipwith each other, as shown in FIG. 22A, as in the solar cell module 20E.According to such an arrangement, the first connection parts 4 c of onesolar cell element 10I and the second connection parts 5 a of the othersolar cell element 10I exist on one straight line. In the solar cellmodule 20I, such first connection parts 4 c and second connection parts5 a are connected using the wirings 11 having a linear form in planview. Also in the present embodiment, the relative arrangementrelationship among the sets of the first connection parts 4 c and thesecond connection parts 5 a in a relationship of being connected withone wiring 11 is equivalent (i.e., the sets of first connection parts 4c and second connection parts 5 a are all in a translationally symmetricrelationship), and thus the wiring 11 having the same shape can be usedfor the connection of each set of the first connection part 4 c and thesecond connection part 5 a. For instance, a wiring having a similarshape to that used in the solar cell module 20A may be used.

In the first connection parts 4 c of the solar cell module 20I formed byconnecting the solar cell elements 10I in this manner, the wirings 11are connected only at the wiring arrangement regions 4 c 1, as shown inFIGS. 22A and 22B, and this realizes a structure in which the wirings 11do not directly contact the through hole arrangement regions 4 c 2formed with the conduction parts 4 b immediately above. Thus, generationof heat contraction stress that may occur in the through holes 3 whenconnecting the wirings 11 to the first connection parts 4 c using hotair, a soldering iron, or a reflow furnace can be alleviated. As aresult, generation of cracks at the through holes 3 having a relativelyweak strength can be reduced.

When the wirings 11 connected to the first connection parts 4 c of onesolar cell element 10I contact the power collecting part 5 b of the samesolar cell element 10I, the first connection parts 4 c and the powercollecting part 5 b short-circuit and cause leakage, and thus aninsulating layer is preferably formed on the power collecting part 5 bat the locations that it contacts the wirings 11. Alternatively, a modeof connecting with wirings similar to the wirings 11B may be adopted.

Furthermore, in the solar cell element 10I, the wiring arrangementregions 4 c 1 and the through hole arrangement regions 4 c 2 of thefirst connection parts 4 c and the second connection parts 5 a may beformed into a shape different from above (e.g., trapezoid, circle,ellipse, semicircle, fan-shape, or composite shape thereof) as long asthe above array state is met and the connection mode by the wirings 11can be realized.

Tenth Embodiment

A solar cell element 10J according to a tenth embodiment of the presentinvention will be described with reference to FIG. 23.

FIG. 23 is a plan view of the solar cell element 10J showing one exampleof electrode patterns of the first electrode 4 and the second electrode5 in the solar cell element 10J when seen from the second surface 1Sside in plan view.

As in the solar cell element 10G′ according to the seventh embodiment,in the solar cell element 10J, the shapes and the arrangementrelationship of the first connection parts 4 c and the second connectionparts 5 a are such that both of them have a longitudinal direction inthe reference direction and are alternately arranged parallel to thereference direction. Furthermore, it is also similar that n−1 pieces offirst connection parts 4 c and n pieces of second connection parts 5 aare arranged. FIG. 23 shows a case of n=4.

However, the solar cell element 10J differs from the solar cell element10G′ in that each first connection part 4 c of the solar cell element10J has a concave-convex shape along the reference direction byalternately arranging two sites of different widths in the referencedirection. Of the two sites, the site having a larger width is referredto as an adhering region 4 c 3, and the site having a smaller width isreferred to as a non-adhering region 4 c 4.

In the case of configuring a solar cell module using a plurality ofsolar cell elements 10J and the wirings 11 (more strictly, a solar cellelement having a structure corresponding to the solar cell element 10Gis also necessary), the solder of the wiring 11 is welded to connect thewiring 11 to the first connection part 4 c only at the adhering regions4 c 3 in the first connection part 4 c. That is, adhesion is performedby points. It is more preferable that each wiring 11 is connected bybeing welded over the entire surface of the first connection part 4 c,but sufficiently satisfactory connection is still realized with the modeof adhesion by points.

In such a mode, the power collecting part 5 b and the high concentrationdoped layer 6 can be formed wider, as shown in FIG. 23, by arranging anon-adhering region 4 c 4 having a narrower width than the adheringregion 4 c 3. That is, the first connection parts 4 c are formed so asto have a concave-convex shape in the reference direction, and then thepower collecting part 5 b and the high concentration doped layer 6 areformed so as to have a concave-convex shape in the reference directionat the interface portions with the first connection parts 4 c. The areaof the formation region of the high concentration doped layer 6 thenincreases, and thus the output characteristics of the solar cell elementis further enhanced.

Eleventh Embodiment

A solar cell element 10K according to an eleventh embodiment of thepresent invention and a solar cell element 10K′, which is a variationthereof, will be described with reference to FIGS. 24A to 24C and FIGS.25A to 25C.

FIGS. 24A to 24C are plan views of the solar cell element 10K showingone example of electrode patterns of the first electrode 4 and thesecond electrode 5 in the solar cell element 10K. FIG. 24A is a diagramof the solar cell element 10K when seen from the second surface 1S sidein plan view, FIG. 24B is a diagram of the solar cell element 10K whenseen from the first surface 1F side in plan view, and FIG. 24C is adiagram of the solar cell element 10K′ when seen from the second surface1S side in plan view.

The solar cell element 10K has a structure that each plurality of (threein FIG. 24A) square-shaped wiring arrangement regions 4 c 5 constitutingportions of the first connection parts 4 c is arranged discretely atsubstantially regular intervals in a plurality of columns (three columnsin FIG. 24A) in the reference direction, and that a plurality of secondconnection parts 5 a is arranged so as to sandwich the respective wiringarrangement regions (first portions of first electrodes) 4 c 5 in eachcolumn. On this point, the solar cell element 10K seems to have aconfiguration similar to the solar cell element 10H according to theeighth embodiment (however, the position of the base sides BS of thesolar cell element 10H shown in FIG. 18A is different by 90° from thatof the solar cell element 10K shown in FIG. 24A). The formation mode ofthe power collecting part 5 b is also similar to the solar cell element10H.

However, the solar cell element 10K differs from the solar cell element10H in that each wiring arrangement region 4 c 5 is continuous with thewiring arrangement region 4 c 5 of another column by a non-wiringarrangement region (second portion of first electrode) 4 c 6 extendingin a direction perpendicular to the reference direction, that is, inthat the first connection parts 4 c have a longitudinal directionperpendicular to the reference direction and concave-convex shapes alongthe direction. In FIG. 24A, the widths of the wiring arrangement region4 c 5 and the non-wiring arrangement region 4 c 6 in the arrangementdirection of a plurality of solar cell elements differ from each other,where the width of the wiring arrangement region 4 c 5 is greater thanthe width of the non-wiring arrangement region 4 c 6.

The first connection parts 4 c and the second connection parts 5 a areformed into sizes with which two wirings 11 can be arranged parallel tothe reference direction when forming a solar cell module 20K to bedescribed later.

Also in the solar cell element 10K, a plurality of conduction parts 4 bis formed in correspondence to a plurality of through holes 3 formed inthe semiconductor substrate 1. As shown in FIG. 24B, the through holes 3(conduction parts 4 b) of the solar cell element 10K are formed so as tobe positioned immediately above along the longitudinal direction(direction perpendicular to the reference direction) of the firstconnection parts 4 c. The main electrode parts 4 a are uniformly formedon the first surface 1F as a plurality of linear patterns connectingwith a plurality of (three in FIG. 24B) conduction parts 4 b positionedin the reference direction.

FIGS. 25A to 25C are diagrams showing the detail of connection betweenthe solar cell elements 10K or between the solar cell elements 10K′ bythe wirings 11 in the solar cell module 20K configured using a pluralityof solar cell elements 10K and the solar cell module 20K′ configuredusing a plurality of solar cell elements 10K′. FIG. 25A is a diagram ofthe two solar cell elements 10K adjacent to each other in the solar cellmodule 20K when seen from the second surface 1S side in plan view, FIG.25B is a diagram of the same when seen from the first surface 1F side inplan view, and FIG. 25C is a diagram of the two solar cell elements 10K′adjacent to each other in the solar cell module 20K′ when seen from thesecond surface 1S side in plan view.

In the case of configuring the solar cell module 20K using the solarcell element 10K in which the first connection parts 4 c and the secondconnection parts 5 a have the above shapes and arrangement relationship,the adjacent solar cell elements 10K are arranged so that the respectivesides BS are positioned in parallel and on the same straight line, andin a translationally symmetric relationship with each other, as shown inFIG. 24A, as in the solar cell module 20H, so that the first connectionparts 4 c of one solar cell element 10K and the second connection parts5 a of the other solar cell element 10K exist on one straight line.

However, in this case as well, when attempting to connect the solar cellelements 10K with the wirings 11 in such a state, the first connectionparts 4 c and the second connection parts 5 a are caused toshort-circuit in one solar cell element 10K, as in the solar cellelement 10H. In order to avoid this, also in the present embodiment, aninsulating layer (not shown) is arranged at sites where connection isnot necessary, similar to the case of configuring the solar cell module20H, and then connection by the wirings 11 is carried out whenfabricating the solar cell element 10K or when configuring the solarcell module 20K. Alternatively, as shown in FIGS. 20A and 20B, the solarcell elements 10K are connected so as to create a clearancecorresponding to the insulating layer using the wirings 11B having abroken folded line shape. Alternatively, the solar cell elements 10K areconnected so as to arrange the insulating layer in the clearance.

In the solar cell element 10K′ shown in FIG. 24C, the first connectionparts 4 c and the second connection parts 5 a are not formed in a partcorresponding to a region where the insulating layer is to be formed ora gap is to be created thereon of the first connection parts 4 c and thesecond connections part 5 a of the solar cell element 10K. Instead, thepower collecting part 5 b is formed in such part. That is, since theregion of the power collecting part 5 b is larger in the solar cellelement 10K′ than in the solar cell element 10K, the outputcharacteristics in the solar cell element 10K′ are further enhanced thanin the solar cell element 10K. However, the first connection parts 4 cand the second connection parts 5 a in the solar cell element 10K′ havethe respective arrangement positions defined so as to realize arotationally symmetric arrangement between the adjacent solar cellelements 10K′ when configuring the solar cell module 20K′.

In the case of configuring the solar cell module 20K′ using the solarcell element 10K′ in which the first connection parts 4 c and the secondconnection parts 5 a have the above shapes and arrangement relationship,the adjacent solar cell elements 10K′ are arranged so that therespective base sides BS are positioned in parallel and not on the samestraight line, and so that they are in a rotationally symmetric (morespecifically, point symmetric) relationship, as shown in FIG. 25C.Accordingly, the first connection parts 4 c of one solar cell element10K′ and the second connection parts 5 a of the other solar cell element10K′ exist on one straight line.

In the solar cell module 20K′ in which a plurality of solar cellelements 10K′ is arranged, the first connection parts 4 c and the secondconnection parts 5 a are connected using the wirings 11 having a linearform in plan view. When the wirings 11 connected to the first connectionparts 4 c of one solar cell element 10K′ contact the power collectingpart 5 b of the same solar cell element 10K′, the first connection parts4 c and the power collecting part 5 b short-circuit and cause leakage,and thus an insulating layer (not shown) is preferably formed on thepower collecting part 5 b at locations where it contact the wirings 11.Alternatively, a wiring similar to the wiring 11B having a plurality ofbent parts in cross-sectional view may be used.

In both the solar cell modules 20K and 20K′, the relative arrangementrelationship among the sets of the first connection parts 4 c and thesecond connection parts 5 a to be connected with one wiring 11 or wiring11B is equivalent (i.e., all the sets of first connection parts 4 c andsecond connection parts 5 a are in a translationally symmetricrelationship), and thus a wiring having the same shape can be used forthe wiring 11 or wiring 11B used in the connection of each set of thefirst connection part 4 c and the second connection part 5 a.

Regarding the solar cell elements 10K and 10K′, the first connectionparts 4 c and the second connection parts 5 a may be formed into a shapedifferent from above (e.g., trapezoid, circle, ellipse, semicircle,fan-shape, or composite shape thereof) as long as the above array stateis met and the connection mode by the wirings 11 can be realized.

(Variation)

Various variations of the solar cell element that can be applied to thesolar cell module according to each embodiment described above of thepresent invention will now be described.

(Extension of the High Concentration Doped Layer and Power CollectingPart)

FIGS. 26A to 26C are diagrams showing a various variations according toa structure in a cross-sectional direction of the solar cell element.

FIG. 26A is a diagram showing a structure of the solar cell element inthe case of extending the formation region of the high concentrationdoped layer 6 up to a position overlapping with the formation region ofthe first connection part 4 c in plan view. This is realized through theprocedures of forming the high concentration doped layer 6 so that itincludes the portion overlapping with the location to be formed with thefirst connection part 4 c (excluding the portion immediately below thethrough hole 3), then, forming an insulating layer 8 a made of an oxidefilm such as silicon dioxide or a nitride film such as silicon nitrideon the overlapped region of the high concentration doped layer 6 withthe location to be formed with the first connection part 4 c, andthereafter forming the first connection part 4 c. Through such aconfiguration, the output characteristics of the solar cell element canbe further enhanced compared to the embodiments described above.

FIG. 26B is a diagram showing a structure of the solar cell element inthe case where not only the high concentration doper layer 6 but alsothe power collecting part 5 b has the formation region extended up to aposition overlapping with the formation region of the first connectionpart 4 c in plan view. This is realized by forming the highconcentration doper layer 6 and the power collecting part 5 bsequentially and so that they include the portion overlapping with thelocation to be formed with the first connection part 4 c (excluding theportion immediately below the through hole 3), then, forming theinsulating layer 8 a so as to cover the overlapped region of the powercollecting part 5 b with the location to be formed with the firstconnection part 4 c, and thereafter forming the first connection part 4c. In addition to the effect of extending the high concentration dopedlayer 6 described above, an effect of reducing the movement distance ofthe carriers collected at the second connection part 5 a and furtherenhancing the output characteristics of the solar cell element isobtained by adopting such a configuration.

FIG. 26C is a diagram showing a structure of the solar cell element, asan application of the structure shown in FIG. 26B, in the case ofarranging a plurality of first connection parts 4 c that is not of bandform (e.g., dot form) so as to form a column in the arrangementdirection of the wiring 11 and moreover extending the high concentrationdoper layer 6 and the power collecting part 5 b between the firstconnection parts 4 c. In this case, the wiring 11 is arranged, otherthan at the connecting location with the first connection part 4 c, onthe insulating layer 8 a such as an oxide film, resin, an insulatingtape, formed on the power collecting part 5 b. In this case as well,similar effects to adopting the structure shown in FIG. 26B areobtained.

FIGS. 27A to 27D are diagrams showing a variation of the arrangement ofthe power collecting part 5 b at the portion that is also arranged at aregion ensured as the non-formation region RE a region where the powercollecting part 5 b is not formed in the solar cell element of eachembodiment described above. FIG. 27A is a plan view showing a variationof the solar cell element 10A according to the first embodiment shown inFIG. 2A, FIG. 27B is a plan view showing a variation of the solar cellelement 10C according to the third embodiment shown in FIG. 6A, and FIG.27C is a plan view showing a variation of the solar cell element 10Daccording to the fourth embodiment shown in FIG. 10A. FIGS. 27A to 27Care all diagrams when seen from the second surface 1S side of thesemiconductor substrate 1 in plan view. FIG. 27D is a cross-sectionalschematic view showing a cross section taken along Y-Y portion of thesolar cell element shown in FIG. 27A. FIGS. 28A to 28C are diagramsshowing a solar cell module formed using the solar cell elementaccording to the variation. FIG. 28A is a plan view of a solar cellmodule in the case where the solar cell element shown in FIG. 27A isused, FIG. 28B is a plan view of a solar cell module in the case wherethe solar cell element shown in FIG. 27B is used, and FIG. 28C is a planview of a solar cell module in the case where the solar cell elementshown in FIG. 27C is used. FIGS. 28A to 28C are all diagrams seen fromthe second surface 1S side of the semiconductor substrate 1 in planview.

Each solar cell element shown in FIGS. 27A to 27C has an insulatinglayer 8 b including an oxide film, resin, an insulating tape, and thelike formed at the location corresponding to the non-formation region REabout the power collecting part 5 b in the solar cell element having thestructure acting as a basis in plan view. More specifically, as shown inFIG. 27D, the power collecting part 5 b is extended at the relevantlocation, and the insulating layer 8 b is arranged so as to cover thesame. The power collecting efficiency of the carrier is thereby furtherenhanced.

Furthermore, by arranging the insulating layer 8 b, an occurrence ofleakage due to the contact of the wiring 11 and the power collectingpart 5 b is reduced as in the case where the non-formation region RE isensured, if the solar cell module is configured using the solar cellelement similar to the corresponding embodiments.

The insulating layer 8 b may be formed by using a thin-film formationtechnique such as a CVD, may be formed by applying and firing aninsulating paste such as a resin paste, or may be formed by attaching acommercially available insulating tape. When firing the insulatingpaste, the insulating paste can be fired and formed simultaneously withthe electrode formation. Alternatively, the insulating layer 8 b may bearranged in advance on the side of the wiring 11 instead on the side ofthe solar cell element, and connection may be made using the same.

<Formation of Finger Part>

FIGS. 29A and 29B and FIG. 30 are diagrams showing a variation of aconfiguration of the solar cell element that the adoption of it enhancesthe power collecting efficiency of the power collecting part 5 b distantfrom the second connection part 5 a in the solar cell element accordingto each embodiment described above.

FIG. 29A is a plan view showing a variation of the solar cell element10A according to the first embodiment shown in FIG. 2A, and FIG. 29B isa plan view showing a variation of the solar cell element 10C accordingto the third embodiment shown in FIG. 6A. FIG. 30 is a plan view showinga variation of the solar cell element 10E according to the fifthembodiment shown in FIG. 12A. FIGS. 29A and 29B and FIG. 30 all show adiagram when seen from the second surface 1S side of the semiconductorsubstrate 1 in plan view.

The solar cell element shown in FIGS. 29A and 29B includes a finger part5 c connecting to the second connection part 5 a and extending up to aregion E of the second surface 1S where the second connection part 5 ais not arranged in the way of going around to the outer periphery of thefirst connection part 4 c. The finger part 5 c is formed using amaterial having lower resistance than the power collecting part 5 b.

In the case where the first connection part 4 c is arranged so as toextend from one side to the other side of the semiconductor substrate 1as in the solar cell element 10A and the solar cell element 10C, thecarrier collected at the region E will be collected at the secondconnection part 5 a with detouring around the first connection part 4 c,if the finger part 5 c is not arranged. The power collection from theregion E can be more efficiently carried out by arranging the fingerpart 5 c having smaller resistance than the power collecting part 5 balong the movement path of the carrier. If the power collecting part 5 bis made of aluminum, the finger part 5 c can be formed using metal suchas silver, copper, or the like as a main component. In particular, whencopper is used for the finger part 5 c, the finger part 5 c can beformed at low cost. The second connection part 5 a and the finger part 5c can be formed with different conductive pastes. For instance, silverpaste may be used for the second connection part 5 a, and copper pastemay be used for the finger part 5 c.

In the solar cell element 10E according to FIG. 30, the finger part 5 cis arranged in the clearance between the first connection parts 4 c. Insuch a case as well, the carrier collected by the power collecting part5 b on the opposite side with respect to the adjacent first connectionpart 4 c can be efficiently transmitted to the second connection part 5a.

<Insulation of Through Hole>

FIG. 31 is a cross-sectional schematic view of a solar cell element 50formed with an insulating material layer 9 made of an oxide film, anitride film, or the like instead of being formed with the secondopposite conductivity type layer 2 b and the third opposite conductivitytype layer 2 c. Specifically, a first insulating material layer 9 a isformed on the surface of the through hole 3, and a second insulatingmaterial layer 9 b made of an oxide film or a nitride film is formed onthe second surface 1S of the semiconductor substrate 1.

The leakage arising between the conduction part 4 b and thesemiconductor substrate 1 is reduced by forming the first insulatingmaterial layer 9 a. The leakage arising between the semiconductorsubstrate 1 and the first connection part 4 c is reduced by forming thesecond insulating material layer 9 b. Furthermore, since the surfacerecombination rate at the second surface 1S of the semiconductorsubstrate 1 lowers through passivation effect when an oxide film or anitride film is formed as the second insulating material layer 9 b, theoutput characteristics of the solar cell element is enhanced.

Specifically, the insulating material layer 9 can be formed by forming asilicon oxide film (SiO₂ film), a titanium oxide film (TiO₂ film), asilicon nitride film (SiNx), and the like to a thickness of about 10 μmto 50 μm using a sputtering method, a vapor deposition method, or a CVDmethod. The oxide film to be the insulating material layer 9 may beformed by performing thermal treatment on the semiconductor substrate 1in a thermal oxidation furnace in an oxygen atmosphere or atmosphericatmosphere, or applying and firing an oxide film material using anapplication method such as spin coating, spraying, or screen printing.The insulating material layer 9 may be a single layer film, or may be amulti-layer including a double layer structure of a silicon dioxide filmand a silicon nitride film.

When containing hydrogen in the insulating material layer 9, thepassivation effect is further enhanced. For instance, since the siliconnitride film formed using a plasma CVD method contains hydrogen (H₂),diffusion of hydrogen (H₂) into the semiconductor substrate 1 by heatingduring film formation or after film formation, and bonding of thehydrogen (H₂) to dangling bond (remaining chemical bond) existing in thesemiconductor substrate 1 reduce the possibility of the carrier beingtrapped by the dangling bond. Therefore, a solar cell element of higherefficiency can be obtained by forming a silicon nitride film oversubstantially the entire surface of the second surface 1S.

In the case of forming the second insulating material layer 9 b oversubstantially the entire surface of the second surface, the oppositeconductivity type layer 2 is less likely to be formed on the backsurface side of the semiconductor substrate 1 when forming the oppositeconductivity type layer (diffusion layer). In particular, it ispreferable to use the CVD method, the application method, or the like,since only the insulating material layer 9 is formed only at the secondsurface of the semiconductor substrate 1.

When forming the first connection part 4 c on the insulating materiallayer 9, the electrode intensity can be enhanced compared to the case offorming the electrode on the semiconductor substrate 1, since theelectrode contains a glass frit.

<Other Variations>

The formation mode of the opposite conductivity type layer 2 is notlimited to the above. For instance, an amorphous silicon hydride film, acrystalline silicon film including a micro crystalline silicon film, andthe like may be formed using a thin-film formation technique. In thecase of forming the opposite conductivity type layer 2 using theamorphous silicon hydride film, the thickness thereof is less than orequal to 50 nm and preferably lower than or equal to 20 nm; and in thecase of forming using the crystalline silicon film, the thicknessthereof is less than or equal to 500 nm and preferably lower than orequal to 200 nm. Furthermore, the i-type (non-dope) silicon region maybe formed between the semiconductor substrate 1 and the oppositeconductivity type layer 2 at a thickness of lower than or equal to 20nm.

The high concentration doped layer 6 may be formed with, e.g., anamorphous silicon hydride film and a crystalline silicon film includinga microcrystalline silicon phase using a thin-film technique. Inparticular, if the pn junction between the opposite conductivity typelayer 2 and the bulk region substrate 1 is formed using the thin-filmtechnique, the formation of the high concentration doped layer 6 is alsopreferably performed using the thin-film technique. In this case, thefilm thickness of the high concentration doped layer 6 is about 10 to200 nm. Furthermore, it is effective to form the i-type silicon regionbetween the semiconductor substrate 1 and the high concentration dopedlayer 6 at a thickness of lower than or equal to 20 nm to enhancecharacteristics.

The application and firing when forming the main electrode part 4 a, theconduction part 4 b, the first connection part 4 c, the secondconnection part 5 a, and the power collecting part 5 b need not beperformed in the order described in the embodiment above. In placethereof, the conductive paste for forming each part may all be appliedand collectively fired to form all the electrodes. Alternatively, themain electrode part 4 a may be applied/fired and formed afterapplying/firing and forming the power collecting part 5 b, the secondconnection part 5 a, the first connection part 4 c, and the conductionpart 4 b. In addition, the procedures may be appropriately combined toform the same. The power collecting part 5 b may be arranged immediatelybelow the second connection part 5 a.

When arranging the insulating layer 8 on the wiring 11, the insulatinglayer 8 may also be arranged at the position to be a clearance betweenthe solar cell elements in the solar cell module. Furthermore, theaesthetic appearance can be improved by coloring the insulating layer 8with a color similar to the back surface protective material 13 and theback side filler 15.

The invention claimed is:
 1. A solar cell module comprising: a pluralityof solar cell elements and a wiring material, each of said plurality ofsolar cell elements comprising: a semiconductor substrate comprising afirst surface for receiving solar light and a second surface on a backside of said first surface; a first electrode comprising a firstconnection part arranged on said second surface of said semiconductorsubstrate; and a second electrode comprising a second connection partarranged on said second surface of said semiconductor substrate, and apower collecting part electrically connected to said second connectionpart, and the first connection part comprises a plurality of firstdivided portions separated from each other and arrayed along an arrayingdirection of the solar cell elements, and each of the first dividedportions is entirely surrounded by the second electrode and apart fromthe second electrode and connected to each other by the wiring material,wherein said wiring material has a linear form in plan view, configuredfor connecting the plurality of solar cell elements arrayed, whereinsaid wiring material is positioned along the arraying direction of thesolar cell elements such that said first electrode and said secondelectrode are sandwiched between said wiring material and saidsemiconductor substrate, and where two adjacent solar cell elements ofsaid plurality of solar cell elements are a first solar cell element anda second solar cell element, and wherein said wiring material isdirectly connected to said first connection part of said first solarcell element and said wiring material is directly connected to saidsecond connection part of said second cell element.
 2. The solar cellmodule according to claim 1, wherein said power collecting part of saidsecond electrode is arranged over substantially an entire surface of aregion not formed with said first electrode and said second connectionpart of said second electrode out of said second surface of saidsemiconductor substrate.
 3. The solar cell module according to claim 1,wherein said wiring material has a bent portion.
 4. The solar cellmodule according to claim 1, wherein said first and second solar cellelements are arranged in a rotationally symmetric relationship with eachother.
 5. The solar cell module according to claim 4, wherein saidsemiconductor substrate comprises a through hole penetrating betweensaid first surface and said second surface, said first electrodecomprises a conduction part arranged in said through hole, and saidfirst connection part of said first electrode comprises a regionconnected to said conduction part of said first electrode and a regionconnected with said wiring material.
 6. The solar cell module accordingto claim 1, further comprising an insulating layer between the secondelectrode and the wiring material.
 7. The solar cell module according toclaim 1, wherein said second connection part of said second electrode isarranged partially overlapping with said power collecting part.
 8. Thesolar cell module according to claim 1, wherein said semiconductorsubstrate comprises a through hole penetrating between said firstsurface and said second surface, and said first electrode comprises alight receiving surface electrode arranged on said first surface and aconduction part electrically connected to said light receiving surfaceelectrode and arranged in said through hole.
 9. The solar cell moduleaccording to claim 1, wherein the semiconductor comprises a first sidealong the arraying direction, and the power collecting part comprises afirst side region located on the first side of the semiconductorsubstrate.
 10. The solar cell module according to claim 9, wherein thesemiconductor comprises a second side along the arraying directionfacing the first side, and the power collecting part comprises a secondside region located on the second side of the semiconductor.
 11. Thesolar cell module according to claim 1, wherein the second connectionpart comprises a plurality of second divided portions separated fromeach other and arranged corresponding to a gap between two adjacentfirst divided portions.
 12. The solar cell module according to claim 11,wherein each of the first divided portions comprises a first edge and asecond edge along the arraying direction, each of the second dividedportions is located on a side of the first edge of the correspondingfirst divided portion, and the second electrode comprises a finger partarranging at a gap between two adjacent first divided portions,electrically connecting the corresponding second divided part, andextending from the corresponding second divided part to a region on aside of the second edge of the corresponding first divided portion inthe collecting part.
 13. The solar cell module according to claim 1,wherein the second electrode comprises a finger part electricallyconnecting to the second connection part and arranged at a gap betweentwo adjacent first divided portions.
 14. The solar cell module accordingto claim 13, wherein the resistance of the finger part is lower that theresistance of the power collecting part.
 15. The solar cell moduleaccording to claim 14, wherein the power collecting part comprisesaluminum and the finger part comprises silver or copper.